Error codes

When a line fails, the engine says two things about it. The message is a sentence for the person reading the note, such as mass and length cannot be added. The code is a short fixed name for the kind of failure, such as INCOMPATIBLE_UNITS, for the program showing the note: it is what a host branches on to underline a line, offer a fix or count failures, without reading the sentence.

The two change on different terms. A message may be reworded in any release. A code a host can receive keeps its name (see versioning and support), so this page only grows.

A code reaches a host in one of three places:

• error.code on the EngineError that evaluateExpression or evaluateLine throws, for a line the engine cannot read or run at all;
• value.errorCode on the error value a line returns, for a line the engine ran but could not answer;
• errorCode on a document line or inline solve from parseDocument or evaluateDocument, for a line that threw, beside its error message, and on the error value in its result for one that returned. See using the engine from TypeScript.

The Arrives column says which way each code comes: thrown, as a value, or either. Either means the engine raises it both ways in different places, or through a helper whose choice depends on the line, so a host should be ready for both.

The same list is in the package, for a program that wants to check a code it has met:

import { ERROR_CODE_CATALOGUES, isCataloguedErrorCode } from "solve-engine/packages";

ERROR_CODE_CATALOGUES.CoreErrorCodes.INCOMPATIBLE_UNITS; // "INCOMPATIBLE_UNITS"
isCataloguedErrorCode("INCOMPATIBLE_UNITS");             // true
isCataloguedErrorCode("CRYPTO_QUERY_FAILED");            // true: a run-time pattern
isCataloguedErrorCode("NOT_A_CODE");                     // false

A package outside this repository can answer with codes of its own, so a code missing from this page is not necessarily a fault: it is one the engine does not ship. The engine and its built-in packages ship 571 codes, grouped below by the part of the engine that raises them.

The engine

CoreErrorCodes

In the package as ERROR_CODE_CATALOGUES.CoreErrorCodes.

Parser

Code	Arrives	When it arises
INVALID_NUMBER_LITERAL	thrown	A number written in a form that does not read as one: a hex, binary or octal literal with a digit its base lacks (0xZZ), or thousands groups that are not three digits long. The reader fixes the digits.
UNTERMINATED_STRING	thrown	A " that is never closed, as in "abc. Raised by the lexer; the reader closes the text.
DIRECTION_CONTROL_IN_NAME	thrown	A name, number or unit holds an invisible character that changes the direction text is shown in (U+202A to U+202E, U+2066 to U+2069, U+200E, U+200F, U+061C), so it would show as something other than what the engine reads. The message names the character by its code point; the reader deletes it. Text in quotes, a comment, a heading and a label keep such characters.
NO_PREFIX_PARSELET	thrown	A line has something where a value should start that cannot start one: the * in 2 + * 3, the ) in round(3.14, ), the > in (5 km) -> miles. Thrown with a span on the character and, where there is an obvious next step, a suggestion.
UNEXPECTED_END_OF_INPUT	thrown	A line stops before its expression does: 5 +, (2 + 3, sqrt(. Thrown with an empty span just after the last character, where an editor puts the caret, and a suggestion.
UNEXPECTED_TOKEN_TYPE	thrown	A form needed one particular thing next and found another: a ) where a , stands, or dice notation (roll 1d6) where a range was expected. Thrown with a span and a suggestion.
NESTING_DEPTH_EXCEEDED	thrown	Brackets, or other nested forms, deeper than the parser allows (validation.maxNestingDepth, 50 by default). A safety limit against input built to exhaust the stack; the reader flattens the line.
UNEXPECTED_END	thrown	The same as UNEXPECTED_END_OF_INPUT, raised where a line ends before an expression starts at all.
UNEXPECTED_TRAILING_TOKEN	thrown	A complete expression followed by more that is not part of it: the , in 1,5 + 1, the 3pm in February 2026 3pm. Thrown rather than answered with the first half, which would be a wrong answer.
PARSE_ERROR	either	The generic parse failure, kept for a caller that wraps one without a more specific code.
TOO_MANY_NUMERIC_CONSTANTS	thrown	One line with more distinct number literals than a compiled program can index. A safety limit; the reader splits the line.
BYTECODE_OPERAND_OUT_OF_RANGE	thrown	A compiled operand outside 0 to 255, or a jump outside the program. A package-authoring fault, reported at compile time rather than letting the program read the wrong constant.
TOO_MANY_STRING_CONSTANTS	thrown	One line with more distinct text literals than a compiled program can index. A safety limit; the reader splits the line.
NO_MATCHING_PHRASE_ALTERNATIVE	thrown	A phrase that starts a form (roll, clamp) followed by none of the words that continue it. The message names the words that may come next.
INVALID_PHRASE_PATTERN	thrown	A package declared a phrase pattern whose alternative does not begin with a keyword. An authoring fault, raised when the pattern is built.
PHRASE_KEYWORD_MISMATCH	thrown	A phrase form missing one of its words part-way through (roll between 1 6, with no and). The message names the word expected.
USER_FUNCTION_INVALID_PARAM_NAME	thrown	A function definition (f(x, y) = ...) with something other than a name where a parameter goes.
USER_FUNCTION_NO_PARAMS	thrown	A function definition with no parameters, f() = ..., which would read the same as a call. A definition needs at least one.
FUNCTION_BODY_MUST_BE_SYNCHRONOUS	thrown	A function definition whose body reaches live data (weather, stocks, a currency rate). Refused when it is defined, since a function body must be synchronous.
FUNCTION_BODY_READS_LINES	thrown	A function definition whose body reads other lines (f(x) = x + prev, x + line 1, a total above, a tag or a table column). Refused when it is defined, since a body runs wherever it is called, with no document lines to read; the value is passed in as an argument instead.
HELD_EXPRESSION_READS_LINES	thrown	A held expression that reads other lines (map(x + prev, 1:3), sum(x + line 1, 1:3), plot x + prev from 0 to 1, der(x^2 + prev, x)). Refused when the line is read, since the expression is worked out away from the line, with no lines to read; the message says to name the line’s value first (p = prev) and use the name.
TOO_MANY_FUNCTION_DEFINITIONS	thrown	One line defining more functions than a compiled program can index. A safety limit, of the same kind as TOO_MANY_NUMERIC_CONSTANTS.
TOO_MANY_ANONYMOUS_BODIES	thrown	One line with more map or reduce bodies than a compiled program can index. A safety limit, of the same kind as TOO_MANY_FUNCTION_DEFINITIONS.
UNKNOWN_PLUGIN_FUNCTION	either	A parselet emitted a call to a plugin function by a name no registered package declares, or before its package registered. A package-authoring or registration fault, not the reader’s line.
PLUGIN_CALL_FAILED	as a value	A plugin function’s promise was rejected. The line reports the rejection’s message rather than waiting again.
PLUGIN_RESULT_NOT_A_VALUE	as a value	A plugin function’s promise resolved to something that is not a Value. An authoring fault, reported on the line.

VM

Code	Arrives	When it arises
EVALUATION_ERROR	thrown	A line failed and no more specific code was kept for it. A fallback; the message says what happened.
INSTRUCTION_LIMIT_EXCEEDED	thrown	One evaluation ran more VM instructions than vm.maxInstructions allows. A safety limit against a line that would run too long; the host may raise the limit.
STACK_LIMIT_EXCEEDED	thrown	One evaluation grew the VM stack past vm.maxStackDepth. A safety limit; the reader simplifies the line.
ALLOCATION_LIMIT_EXCEEDED	thrown	One evaluation asking for more elements (list cells, matrix cells) than vm.maxAllocatedElements allows, even inside a single operation. A safety limit that describes this line; the host may raise it.
STACK_UNDERFLOW	thrown	The VM read more values than its stack held: corrupted bytecode or a faulty plugin. Worth reporting; the engine stays usable and only this line fails.
UNDEFINED_VARIABLE	thrown	A line reads a name no line above defines. Thrown with no span, and with the nearest defined names in suggestion and context.didYouMean when there are any.
GLOBAL_VARIABLE_NOT_RESOLVED	thrown	A global :name read before its value arrived from the shared store. It resolves on a later evaluation.
UNKNOWN_FUNCTION	thrown	A call to a name that is not a function the engine or a package provides. The nearest names are offered where there are any.
UNEXPECTED_PENDING_RESULT	thrown	A caller that asked for a settled value was handed one still waiting on live data. A caller-contract fault inside the engine, worth reporting.
UNDEFINED_FUNCTION	either	A call to a function of the reader’s own that no line defines, or a definition the VM could not complete.
FUNCTION_ARITY_MISMATCH	either	A function of the reader’s own called with a different number of arguments than it was defined with.
BUILTIN_ARITY_MISMATCH	thrown	A built-in function called with the wrong number of arguments: sqrt(), atan2(1), sqrt(1, 2, 3). Separate from FUNCTION_ARITY_MISMATCH, so a host can word the two differently.
USER_FUNCTION_ASYNC_UNSUPPORTED	thrown	A function of the reader’s own whose body reaches live data (weather, stocks, a currency rate). Function bodies must be synchronous.
MAP_REDUCE_ASYNC_UNSUPPORTED	thrown	A map or reduce body that reaches live data while it runs. Refused at parse time first (MAP_REDUCE_TRANSFORM_MUST_BE_SYNCHRONOUS); this is the run-time guard.
SYMBOLIC_ASYNC_UNSUPPORTED	thrown	An algebra verb’s expression that reaches live data while it runs. Refused at parse time first (SYMBOLIC_ARGUMENT_MUST_BE_SYNCHRONOUS); this is the run-time guard.
EXPLAIN_ASYNC_UNSUPPORTED	thrown	explainLine() asked to derive a line that resolves data asynchronously (a live-data or async-plugin line). A derivation is a sequence of settled intermediate values, which a pending result has none of, so the line is refused rather than explained with a hole in it.
TRACE_NO_DOCUMENT	thrown	traceLine() called with no document to read: the engine has no attached document model and no parseDocument result was passed as options.document. A trace follows one line into the lines above it, so without a document there is nothing to follow.
TRACE_NO_SUCH_LINE	thrown	traceLine() asked for a line number the document does not have (below 1, past the last line, or not a whole number).
FUNCTION_RECURSION_LIMIT_EXCEEDED	thrown	A function of the reader’s own that calls itself too deeply, as f(x) = f(x) does. Refused by name rather than overflowing the native stack.
FUNCTION_CALL_LIMIT_EXCEEDED	thrown	One evaluation making more calls to functions of the reader’s own than the budget allows, however shallow each call is. A safety limit against a chain of functions that multiplies its calls.
DATE_OFFSET_LIMIT_EXCEEDED	thrown	A <date> + N workdays offset outside date.maxOffsetYears and date.minOffsetYears. Workdays walk the calendar a day at a time, so their cost is the offset.
WORKDAY_OFFSET_EXPECTED_DATE	as a value	N working days after <x> (or before, from) where <x> is not a date, as in 5 working days after 3.
WORKDAYS_BETWEEN_EXPECTED_DATES	as a value	working days between <a> and <b> where one end is not a date.
WORKDAYS_BETWEEN_RANGE_TOO_LARGE	as a value	working days between two dates further apart than date.maxOffsetYears and date.minOffsetYears allow the count to walk.
BIGINT_SHIFT_LIMIT_EXCEEDED	thrown	A << or >> on a big integer whose exact result would be too large to compute. Refused rather than answered in doubles as Infinity.
BIGINT_POW_LIMIT_EXCEEDED	thrown	A ^ on a big integer whose exact result would be too large to compute (2n ^ 100000). Refused rather than answered as Infinity; a fractional or negative exponent uses doubles instead.
BIGINT_INEXACT_OPERAND	thrown	A value with no whole-number form (a fraction, an infinity) meeting a big integer: 1n + 0.5, 5n / pi.
BIGINT_DIVISION_BY_ZERO	thrown	10n / 0n or 10n mod 0n. A big-integer division is exact, and an exact division by zero has no answer, unlike 1 / 0, which is Infinity.
BASE_NOT_FINITE	as a value	An infinity or a result with no value written in a base: (1/0) in hex, 2^4000 in binary, hex(1/0). It has no digits; a whole number written with n (2n^4000) keeps every digit.
INTERNAL_MISSING_FUNCTION_BODY	thrown	A compiled program naming a function body it does not carry. A compiler or VM fault, worth reporting.
INTERNAL_MISSING_ANONYMOUS_BODY	thrown	A compiled program naming a map or reduce body it does not carry. A compiler or VM fault, worth reporting.
UNKNOWN_BUILTIN_FUNCTION	as a value	A compiled call to a built-in function at an index none is registered at. Reachable only through a compiler or snapshot fault; worth reporting.

Malformed bytecode

Code	Arrives	When it arises
MALFORMED_BYTECODE_TRUNCATED	either	An operand byte read past the end of the stream: the program ends in the middle of an instruction.
MALFORMED_BYTECODE_CONSTANT_INDEX	either	A constant-pool operand indexing a numbers/strings entry that does not exist, or that is not of the pool’s type.
MALFORMED_BYTECODE_OPERAND_TYPE	either	A unit or converter name read off the value stack that is not a string. Distinct from the pool case above: the operand is a Value another opcode pushed, not a pool entry.
MALFORMED_BYTECODE_BODY_KIND	either	A map or reduce instruction carrying a body kind other than 0, 1 or 2.
MALFORMED_BYTECODE_BIGINT_LITERAL	either	A big-integer constant in the program that is not a whole number, such as "1.000".
MALFORMED_BYTECODE_PROGRAM	thrown	executeBytecode called with something that is not a runnable program at all.
MALFORMED_BYTECODE_UNKNOWN_OPCODE	either	An instruction the VM does not have, refused at the offset that carries it (in the error’s context).

Symbolic algebra

Code	Arrives	When it arises
SYMBOLIC_RATIONAL_OVERFLOW	thrown	A coefficient grew past RATIONAL_MAX_BITS, e.g. repeated exact elimination multiplying denominators together.
SYMBOLIC_NONFINITE_OPERAND	either	NaN or ±Infinity reaching a symbolic expression, neither of which has an exact rational value.
SYMBOLIC_DIVISION_BY_ZERO	either	An exact symbolic division by zero, such as expand((x+1)/0): refused where the quotient is written, as a value, and thrown from the rational arithmetic beneath. The zero is exact, so a very small number is not mistaken for one.
SYMBOLIC_QUANTITY_OPERAND	as a value	Arithmetic between an unknown and an amount with a unit, such as foo * 5 km =>: a formula has nowhere to keep the unit, so the line is refused rather than answered with the unit dropped.
SYMBOLIC_NODE_LIMIT_EXCEEDED	thrown	A tree exceeding SYMBOLIC_MAX_NODES entering the simplifier.
SYMBOLIC_FORMULA_VALUE_UNSUPPORTED	as a value	A name holding a formula written before one of its unknowns had a value (y = x + 1 above x = $5), read after that unknown was given money, a quantity in a unit, a date or text, which the formula cannot take. Returned by the read rather than a formula mixing the value with the unknown (#732).
SYMBOLIC_UNSUPPORTED_FUNCTION	as a value	A builtin with no symbolic reading (min, random, the finance block, …) applied to an expression still containing an unknown. Returned rather than computing against toNumber()’s placeholder zero.
SYMBOLIC_FACTOR_LIMIT_EXCEEDED	thrown	factor of a cubic or higher whose rational roots cannot be searched: a coefficient too long a fraction to list its divisors (factor(x^3 - pi)), or a candidate set past FACTOR_MAX_ROOT_CANDIDATES. A quadratic is decided by its discriminant instead and never raises it.
SYMBOLIC_SOLVE_UNSUPPORTED	as a value	An equation outside what the solver attempts: above the degree ceiling, non-linear in the unknown while another unknown is present, or not a polynomial and not evaluable numerically either (another unknown in it, an imaginary constant, a function with no numeric form). A non-polynomial equation in one unknown is solved numerically instead (see symbolic/NumericSolve.ts).
SYMBOLIC_SOLVE_INCOMPLETE	as a value	Some but not all of an equation’s roots were found. Reported rather than returned, because a partial list of roots looks exactly like a complete one.
SYMBOLIC_SOLVE_NO_ROOT_FOUND	as a value	A numerically solved equation whose two sides never cross in the range searched. Not “no solution”: a search that found nothing has not shown there is nothing, and the message names the range and what the search cannot see.
SYMBOLIC_SOLVE_TOO_MANY_ROOTS	as a value	A numerically solved equation with more roots in the range than NUMERIC_ROOTS_MAX, as a periodic one has, or whose two sides compare equal across a whole stretch. Declined rather than listed, because a list cut off at the edge of the search would read as complete.
SYMBOLIC_BOUND_INVALID	as a value	A bound of integral, an end of solve’s search range, or limit’s point that is not a plain finite number: it carries a unit, still contains an unknown, is not a number, or (for solve and limit) is infinite.
SYMBOLIC_REQUIRES_BOTH_BOUNDS	thrown	integral(f, x, a) or solve(eq, x, a): one number after the unknown where the form takes two. A parse error naming the form, rather than a missing closing parenthesis.
SYMBOLIC_REQUIRES_LIMIT_POINT	thrown	limit(f, x) with no point for the unknown to approach.
SYMBOLIC_INTEGRAL_IMPROPER	as a value	A definite integral with an infinite bound, or whose integrand has no finite value somewhere in the range (1/x from 0 to 1). Improper integrals are refused by name rather than evaluated.
SYMBOLIC_INTEGRAL_UNSETTLED	as a value	A definite integral whose numeric estimate did not settle within the quadrature’s budget, which is what an integrand growing without bound inside the range, and so a diverging integral, looks like.
SYMBOLIC_LIMIT_DIVERGES	as a value	A limit where the expression grows without bound (1/x^2 at 0).
SYMBOLIC_LIMIT_SIDES_DISAGREE	as a value	A limit whose left and right sides settle on different values (abs(x)/x at 0). The message names both.
SYMBOLIC_LIMIT_UNSETTLED	as a value	A limit whose values never settle on one number (sin(1/x) at 0).
SYMBOLIC_LIMIT_UNDEFINED	as a value	A limit of an expression with no real value near the point on either side.
SYMBOLIC_LIMIT_UNSUPPORTED	as a value	A limit of an expression that cannot be evaluated numerically: another unknown in it, an imaginary constant, or a function with no numeric form.
SOLVE_REQUIRES_VARIABLE_NAME	either	solve’s second argument not being a bare name.
SYMBOLIC_DERIVATIVE_ORDER_LIMIT	thrown	A derivative order outside 0..DERIVATIVE_MAX_ORDER.
SYMBOLIC_INTEGRAL_UNSUPPORTED	as a value	An indefinite integral with no known elementary antiderivative, reported rather than approximated, since a wrong integral is indistinguishable from a right one at the point of use. For a definite integral, one with no antiderivative that also cannot be evaluated numerically (another unknown in it, or a function with no numeric form).
SYMBOLIC_TAYLOR_DEGREE_LIMIT	thrown	A Taylor degree outside 0..TAYLOR_MAX_DEGREE.
SYMBOLIC_TAYLOR_INEXACT	thrown	A Taylor coefficient that does not reduce to an exact number at the expansion point.
SYMBOLIC_REQUIRES_VARIABLE_NAME	either	An algebra verb’s variable-name argument not being a bare name.
SYMBOLIC_JACOBIAN_NO_VARIABLES	as a value	jacobian called with expressions containing no unknown to differentiate against.
INTERNAL_RATIONAL_PARSE	thrown	A finite number whose decimal form could not be read back, which the regex covering every Number.prototype.toString output should make unreachable.

Engine

Code	Arrives	When it arises
EXPRESSION_TOO_LONG	thrown	A line longer than validation.maxExpressionLength characters. Refused before it is read; the host may raise the limit.
EXPRESSION_TOO_COMPLEX	thrown	A line whose complexity score passes validation.maxComplexity. Refused before it is read; the host may raise the limit.
DOCUMENT_TOO_LARGE	thrown	A document with more lines than performance.maxDocumentLines. The per-line limits above bound what one line may ask for and say nothing about how many lines there are; two hundred thousand of 1 + 1 exhausted the heap on the line records alone. Recoverable.
NORMALIZED_TOKEN_LIMIT_EXCEEDED	thrown	The normaliser grew a line’s tokens past its safety limit. A guard against a rule that expands without end.
NORMALIZER_PASS_LIMIT_EXCEEDED	thrown	The normaliser was still changing the token stream after its pass budget (maxPasses, 100 by default): a rule chain that never settles. Reported rather than returning whatever the last pass left. Recoverable.
THEREFORE_REQUIRES_EXPRESSION	thrown	"=>" with nothing before it, needs an expression or variable name to solve/simplify.
THEREFORE_ASYNC_UNSUPPORTED	thrown	A "=>"-triggered expression called an async plugin (weather/stocks/currency). Same v1 scope restriction as user-function/map-reduce bodies.
COMPOUND_ASSIGN_REQUIRES_EXPRESSION	thrown	A compound assignment (name += expr / name -= expr) with nothing on the right, a line half-typed on the way to total += 5.
COMPOUND_ASSIGN_ASYNC_UNSUPPORTED	thrown	A running total (+= / -=) whose right-hand side calls an async plugin (weather/stocks/currency). The same v1 scope restriction as the "=>" and user-function bodies.
UNKNOWN_SAVINGS_PERIOD	thrown	A savings-goal contribution period that is not one of daily/weekly/monthly/yearly (how long to save $X at $Y <period>). Names the accepted set.
INVALID_TIME_LITERAL	thrown	Colon-separated numbers that are not a time any clock can show (“24:00”, “9:60”, “100:5”). Raised by the labeled-line fallback, which used to answer them with whatever stood after the colon.
TERNARY_UNSUPPORTED	either	A choice written condition ? value : other (true ? 25 : 30). There is no such operator; the message spells the line as if ... then ... else. Raised by the labelled-line fallback, which used to read true ? 25 as a label and answer 30.
LABEL_NOT_A_NAME	either	Text before a colon that is a comparison, an assignment, or a calculation or bracketed figure with no word in it (a > b: 1, (1+2): 5, (24):00), so not a label naming the figure after it. Raised by the labelled-line fallback, which used to answer with the figure whatever the text said.
OTHER_SCRIPT_DIGITS	either	A figure in digits from another script (٢٤:00, Total: ٢٤:00, Arabic-Indic for 24) standing before a colon where a number would be an operand. Numbers are read in the digits 0 to 9 only, and the labelled-line fallback used to take the figure as a label and answer with what followed the colon. The message spells the figure in 0 to 9.
INVISIBLE_CHARACTER_IN_NUMBER	either	A figure in 0 to 9 holding an invisible character that is not a direction control (a zero-width joiner or non-joiner, a word joiner, a soft hyphen), standing before a colon where a number would be an operand (<U+200D>24:00). The character makes the figure a word, which the labelled-line fallback used to take as a label and answer with what followed the colon. The message names the character by its code point; the reader deletes it. A direction control in the same place is DIRECTION_CONTROL_IN_NAME.
NETWORK_DISABLED	as a value	A live-data form evaluated on an engine whose host switched the network off (network.enabled: false, see constants/Configuration.ts’s NetworkConfig). A recoverable Error value, raised by the VM for a currency conversion with no primed rate and for a plugin function that returned a promise, and by createQueryResolver’s plugin function when its preflight was skipped. Names the setting, so the reader knows it is policy rather than an outage.

What-if

Code	Arrives	When it arises
WHAT_IF_OVERRIDE_INVALID	thrown	engine.whatIf(text, overrides) was given an override whose name is not a variable name, or whose value is not a finite number, text that evaluates on its own, or a Value. Thrown, since it is the host’s argument that is wrong rather than a line of the note.
WHAT_IF_INPUT_NOT_USED	either	A what-if overrides a name no line it re-runs mentions, which cannot change any answer and is almost always a misspelling. Thrown by engine.whatIf; returned as an Error value by the line N with ... and sweep forms.
WHAT_IF_WRITES_GLOBAL	either	A what-if would re-run a line that sets a global :name. A global is shared with every other document in the process, so the scenario’s value would reach them; refused rather than re-run. Thrown by engine.whatIf; returned as an Error value by the line forms.

Frozen answers

Code	Arrives	When it arises
FROZEN_VALUE_MISSING	as a value	A line ending frozen on <day> whose engine holds no value frozen that day, and the day is not today. A recoverable Error value, raised by the VM in place of running the line: a frozen answer is never fetched again, so the line is refused rather than frozen at today’s figure. The message names the day, and the day of the value that is stored when there is one.
FROZEN_UNSUPPORTED	thrown	frozen on a line with no single answer to keep: a function definition, a global cell write, or a definition part-way through the line. Raised at compile time, naming the shape.
FROZEN_DATE_EXPECTED	thrown	frozen on followed by something that is not a single date at the end of the line (frozen on tuesday, a bare frozen on). Raised at compile time, with an example of the form. A day that does not exist (frozen on 2026-02-30) reports the date literal’s own error instead.

Temporal calendar backend

Code	Arrives	When it arises
TEMPORAL_IMPLEMENTATION_INVALID	thrown	createTemporalCalendar() was handed something that is not a usable Temporal implementation: no Now.instant, Now.timeZoneId, Instant.fromEpochMilliseconds or PlainDateTime.from. Raised at construction, naming the missing member, rather than letting the first date computation fail on it obscurely.
TEMPORAL_TIME_ZONE_UNKNOWN	thrown	The timeZone given to createTemporalCalendar() is not one the Temporal implementation knows. Raised at construction, so a misspelt zone is a configuration error the host sees once, not a RangeError from inside every date the engine computes.

Calendar backend clocks

Code	Arrives	When it arises
DATE_CLOCK_INVALID	thrown	The clock a host gave a calendar backend (dateCalendarInZone(zone, { now }), createTemporalCalendar(Temporal, { now })) is not a function, answered something that is not a moment Date can hold (NaN, an infinity, a number past 8.64e15, not a number), or threw. Not a function is refused when the backend is built; a bad reading is refused on the line that read the clock (today, now), and the rest of the document goes on (#721, #826).

Snapshot / restore

Code	Arrives	When it arises
SNAPSHOT_VERSION_MISMATCH	thrown	fromJSON() handed an object that is not a snapshot at all, or whose serialised-shape version does not match this engine’s reader. The versioning gate that refuses an incompatible snapshot clearly rather than restoring it wrongly. See engine/EngineSnapshot.ts’s assertRestorable().
SNAPSHOT_MALFORMED	thrown	A snapshot with the right envelope but internally inconsistent contents (an unrecognised number sentinel, an unknown value tag). Distinct from a version mismatch: the format is right, the payload is not.
SNAPSHOT_UNSUPPORTED_VALUE	thrown	A value the snapshot format cannot yet represent (a symbolic value or matrix cell, a colour, a split, a chart, an IP subnet). toJSON catches it and leaves the value out (#665).
SNAPSHOT_PACKAGE_MISSING	thrown	A snapshot calls a plugin function that no package registered on the restoring engine provides. Refused rather than restored, since the call would run whatever sits at its old index (#658).

Config

Code	Arrives	When it arises
CONFIG_PATH_NOT_FOUND	thrown	A configuration read or write named a path that does not exist. A host configuration fault.
INVALID_CONFIG_PATH	thrown	A configuration path not in the section.property form. A host configuration fault.
CONFIG_SECTION_NOT_FOUND	thrown	A configuration path whose section does not exist. A host configuration fault.
CONFIG_PROPERTY_NOT_FOUND	thrown	A configuration path whose property does not exist in its section. A host configuration fault.

Forms and settings without a catalogue of their own

Code	Arrives	When it arises
CALENDAR_TEMPORAL_UNAVAILABLE	thrown	calendar: "temporal" was asked for on a runtime with no Temporal. Refused rather than silently computing on Date, because a host that named Temporal did so to be sure what it was computing on. Recoverable.
TRIP_EXPECTED_AT	thrown	A trip form (cost to drive ...) was written without the at that separates its parts. Recoverable.
DIMENSIONS_EXPECTED_FORM	thrown	A width and a height were written with nothing asked of the pair (1920x1080 on its own). Recoverable.
RESIZE_EXPECTED_SHAPE	thrown	A resize was written without one of its parts: the dimensions, the to, the size, or the side it names. Recoverable.

Registering a package

Code	Arrives	When it arises
PLUGIN_OPERATOR_COLLISION	thrown	A package registered an operator the engine already has. Refused at registration, since a built-in operator cannot be overridden.
PLUGIN_OPERATOR_UNSUPPORTED	thrown	A package registered an operator the scanner cannot read: not exactly two characters, or a first character the scanner does not class as an operator. Refused at registration rather than left to never fire.
PLUGIN_KEYWORD_COLLISION	thrown	A package registered a keyword the engine already has. Refused at registration, since a built-in keyword cannot be overridden.
PLUGIN_CALL_FUSION_UNREACHABLE	thrown	A package’s callFusions names a word the engine already reads as something other than a plain word (a keyword, a built-in function, a unit), so the call could never fire. Refused at registration.
PLUGIN_UNIT_ALIAS_UNREACHABLE	thrown	A package’s unitAliases names a word the engine already reads as something other than a plain word (a unit, a keyword, a function), so the alias could never be read. Refused at registration (#762).
PLUGIN_UNIT_ALIAS_TARGET_UNKNOWN	thrown	A package’s unitAliases maps a word to something that is not a single unit the engine reads (mile, days), so the alias would have nothing to mean. Refused at registration (#762).
PLUGIN_UNIT_COLLISION	thrown	A package registered a unit spelling the engine already has. Refused at registration, since a built-in unit cannot be overridden.
PACKAGE_ENGINE_VERSION_MISMATCH	thrown	A package’s declared IEnginePackage.engineVersion semver range doesn’t satisfy the running engine’s ENGINE_VERSION. See api/EngineVersionCompatibility.ts.
PACKAGE_ENGINE_VERSION_INVALID_RANGE	thrown	A package’s declared IEnginePackage.engineVersion isn’t a parseable semver range at all (a typo in the package’s own descriptor).
PACKAGE_NAME_MISSING	thrown	A package was registered with no name, or an empty one, so nothing could name it to unregister it or report on it (#719).
PACKAGE_RESOLVER_FUNCTION_MISSING	thrown	A package’s createQueryResolver watches for a plugin function the package does not declare, or was built for another package, so the call it waits for would never come (#719).
OPCODE_POOL_EXHAUSTED	thrown	More packages asked for opcodes of their own than the dynamic opcode range holds. A registration fault.
PLUGIN_FUNCTION_INDEX_POOL_EXHAUSTED	thrown	More plugin functions registered than a compiled call can index (65,536). A registration fault.
PLUGIN_FUNCTION_INDEX_TOO_LARGE	thrown	A plugin function’s index past the largest a compiled call can hold (65,535). A registration fault.

Value contracts: a caller checks isRateUnit() or isTimecodeUnit() first

Code	Arrives	When it arises
INVALID_RATE_UNIT	either	A rate unit read or built from parts that do not make one: a caller-contract fault inside the engine or a package, or x/y where x is already a rate.
INVALID_TIMECODE_UNIT	thrown	A timecode unit read from a string that is not one. A caller-contract fault inside the engine or a package.

Exact decimals

Code	Arrives	When it arises
INVALID_DECIMAL_LITERAL	thrown	Text read as an exact decimal that is not one. Raised while a number literal is compiled; the reader fixes the digits.
DECIMAL_DIVISION_BY_ZERO	thrown	An exact decimal division reached the decimal layer with a zero divisor. An engine invariant: the operators refuse a zero divisor first, so this is worth reporting.
DECIMAL_INVALID_SCALE	thrown	An exact decimal built with a negative or fractional scale. An engine invariant, worth reporting.
DECIMAL_NEGATIVE_POWER	thrown	A power of ten asked for with a negative exponent inside the decimal layer. An engine invariant, worth reporting.

Units and quantities

Code	Arrives	When it arises
INCOMPATIBLE_UNITS	as a value	Two quantities that do not measure the same thing met where they must: 5 kg + 3 m, 5 kg to m. The message names both measures.
UNKNOWN_UNIT	as a value	A conversion or a unit named something that is not a unit (5 km in mies). The message offers the nearest spellings where there are any.
UNIT_AFTER_UNIT	as a value	A quantity followed by a second unit, as in 5 kg m: two units side by side are not a unit. The message suggests in for a conversion.
UNIT_IN_EXPONENT	as a value	An exponent carrying a unit, as in 2^(3 m). The message shows where the unit goes instead.
UNIT_POWER_UNSUPPORTED	either	A quantity raised to a power that has no unit, as in 2s^2, or a unit written with a power the table does not spell. Only a length squared or cubed has one. A variance of quantities other than lengths, or of percentages, is refused with it too.
UNIT_ROOT_UNSUPPORTED	as a value	A square or cube root of a quantity whose root has no unit, as in sqrt(4 m), or of a negative area.
UNIT_PRODUCT_UNSUPPORTED	as a value	Two quantities multiplied into something that is not a unit, as in $5 * $3. Lengths multiply into an area or a volume.
UNIT_QUOTIENT_UNSUPPORTED	as a value	Two quantities divided into something that is not a unit: nothing cancels and the result would be a rate of a rate.
UNIT_RECIPROCAL_UNSUPPORTED	as a value	A number divided by a quantity with no reciprocal unit, such as a temperature.
CONVERT_NON_NUMERIC	as a value	Something with no single amount (a list, text, a date) converted to a unit.
QUANTITY_NON_NUMERIC	as a value	Something with no single amount combined with a quantity, as in a list plus 5 m.
CONSTANT_UNIT_UNSUPPORTED	as a value	A physical constant whose unit the engine cannot spell yet, converted or combined with a quantity. The constant stays a plain number.
CURRENCY_RATE_UNAVAILABLE	as a value	A conversion between two currencies with no exchange rate available for the pair. A host with live data may prime a rate and evaluate again.
RATE_MISSING_DENOMINATOR_UNIT	as a value	A rate built with / whose right-hand side has no unit to be per.
RATE_MUL_LEFT_NOT_A_RATE	as a value	A rate multiplication whose left-hand side is not a rate.
RATE_MUL_RIGHT_MISSING_UNIT	as a value	A rate multiplied by a value with no unit matching what the rate is per.
RATE_MUL_MEASURE_MISMATCH	as a value	A rate multiplied by a quantity that measures something else than what the rate is per ($50/week * 3 kg).
RATE_CONVERT_NOT_A_RATE	as a value	A conversion of a rate’s denominator applied to a value that is not a rate.
RATE_CONVERT_MEASURE_MISMATCH	as a value	A rate’s denominator converted to a unit that measures something else ($50/week in kg).
UNCERTAINTY_WITHOUT_UNIT	as a value	A value with a tolerance (5 m +/- 1 cm) converted to a unit or combined with a quantity: a tolerance is read without its unit.
UNCERTAINTY_UNIT_MISMATCH	as a value	A tolerance whose unit does not measure what its value does, or that has no rate to reach the value’s currency.

Arithmetic and functions

Code	Arrives	When it arises
TEXT_ARITHMETIC	as a value	Text used in arithmetic with a number, written after a sign (-"abc"), or given to a numeric function (sqrt("abc")). The message points at as number for text that holds a number.
TEXT_COMPARISON	as a value	Text in an order comparison ("5" > 3, "a" < "b"): text has no order a note would mean. Against a number the message says which side is text and, for text that holds a number, points at as number.
COLOUR_ARITHMETIC	as a value	A colour in arithmetic, a numeric function, an order or a conversion to a form of a number (#ff0000 + 2, sqrt(#ff0000), #ff0000 < 3). A colour is three channels, not one number; the message points at reading a channel out, as in red(#3366cc).
IPV6_ARITHMETIC	as a value	An IPv6 address in arithmetic, a numeric function, a comparison with a number or a conversion with no whole-number reading (fe80::1 + 2). Its 128 bits are past what a number holds exactly; the message points at as int.
TEXT_NOT_A_NUMBER	as a value	as number or int given text that is not a number.
REMAINDER_UNDEFINED	as a value	A remainder with no value: 5 mod 0, or the remainder of an infinite number.
QUOTIENT_UNDEFINED	as a value	A division with no single answer: 0 / 0 (either zero signed), or an infinity over an infinity. 5 / 0 is ∞ and is not refused.
POWER_NO_REAL_VALUE	as a value	A negative number to a fractional power with no real value, as in (-1)^0.5, or a negative number’s root of even degree.
FUNCTION_DOMAIN	as a value	A function called outside the numbers it is defined for, such as ln(0). The message names the domain.
FUNCTION_TAKES_NUMBER	as a value	A function that takes plain numbers given a quantity, as in sin(1 m), or a mix of numbers and quantities.
TRIG_UNDEFINED	as a value	tan at an odd multiple of a right angle, where the tangent has no value.
NOT_WHOLE_NUMBER	as a value	A function that counts whole things (fact, nPr) given a fraction.
INVALID_FACTORIAL_INPUT	as a value	A factorial of a negative number or a fraction.
FACTORIAL_OVERFLOW	as a value	A factorial past 170!, the largest a double can hold.
PERMUTATION_OVERFLOW	as a value	A permutation count past the largest number a double can hold.
COMBINATION_OVERFLOW	as a value	A combination count past the largest number a double can hold.
INVALID_RANGE	as a value	A range given backwards where order matters: a roll from 6 to 1, or a permutation or combination with more chosen than there are.
INVALID_INTEGER_OPERAND	as a value	gcd or lcm given a number with no whole value (an infinity, or nothing).
NUMBER_THEORY_EXPECTED_INTEGER	as a value	A number theory function (factor, isprime, modpow) given something that is not a whole number.
NUMBER_THEORY_DOMAIN	as a value	A number theory function given a whole number outside what it is defined for: factor(0), a modulus below 1, a negative exponent.
NUMBER_THEORY_NO_INVERSE	as a value	modinv of a number that shares a factor with the modulus, so no inverse exists.
FACTOR_TOO_LARGE	as a value	factor of a whole number past 2^64, which is refused rather than left to run.
PROPORTION_DIVIDE_BY_ZERO	as a value	proportion whose first term is zero, so there is nothing to scale by.
WEIGHTED_AVERAGE_ZERO_WEIGHT	as a value	A weighted average whose weights add up to zero.
STATISTIC_NOT_FINITE	as a value	A standard deviation or variance of a list holding an infinity.
AGGREGATE_NON_NUMERIC	as a value	A list aggregate (total of, average of, a line range) meeting something that is not a number or a quantity. The message names what it found.
AGGREGATE_PERCENTAGE_MIXED	as a value	An aggregate (sum(10%, 100), average of 10%, 5 m, max(10%, 0.5), total above over a column) meeting a percentage beside a value that is not one. Percentages alone answer a percentage (sum(10%, 20%) is 30%); the message names the percentage and the kind of the other value, and gives the percentage as the number it stands for.
PERCENTAGE_OF_QUANTITY	as a value	A value written as a percentage that is not a proportion, such as a length.
PERCENTAGE_NOT_FINITE	as a value	A value written as a percentage that is not a finite number: an infinity a division by zero gave (1/0 as %), or a value that is no number at all.
PERCENTAGE_OVERFLOW	as a value	A value written as a percentage that is too large for its percentage, a hundred times it, to be held, as in 1e308 as %, or that is itself past the largest number that can be held, as in 2^2000 as %.
PERCENT_CHANGE_FROM_ZERO	as a value	A percentage change from zero, which no percentage reaches. The message suggests the difference instead.
PERCENT_CHANGE_NEGATIVE_BASE	as a value	A percentage change from a negative base, which has two readings. The message shows how to write the one meant.
PERCENT_CHANGE_FAILED	as a value	A percentage change that could not be worked out from its two values.
INVALID_RATE	as a value	A rate of interest or inflation that cannot be used: not a percentage, not finite, or at or below -100%.
INVALID_TERM	as a value	A loan or savings term that is not a length of time.
INFLATION_YEAR_OUT_OF_RANGE	as a value	An inflation adjustment for a year outside the bundled price index.
INVALID_DATETIME_OP	as a value	A date moved by a plain number, or by a quantity that is not a length of time, or to between a date and something that is not one. The message says what a date moves by.
TIMECODE_FPS_MISMATCH	as a value	Two video timecodes at different frame rates added or subtracted.
UNKNOWN_AS_CONVERTER	as a value	as <name> naming no converter any package registered.
FLOAT_TAKES_NUMBER	as a value	float("hello"), float(5 km): float given something with no plain number, text that is not a number or a quantity with a unit. The reader passes a number (#828).
MULTIPLIER_TAKES_NUMBER	as a value	"hello" as multiplier, 5 km as multiplier: a multiplier asked of something that is not a plain number or a percentage. The reader converts a number (#829).
AS_CONVERTER_AMBIGUOUS_CASE	as a value	as mw: the target, read regardless of case, could be two units whose prefixes differ only in case (mW and MW), so it is refused rather than guessed (#824).
AS_CONVERTER_PREFIX_CASE	as a value	as MV when only mV is a unit: reading it regardless of case would turn a mega into a milli, so it is refused by name (#824).
PLOT_INVALID_RANGE	as a value	A plot’s range whose ends are not finite numbers.

Lists, ranges and matrices

Code	Arrives	When it arises
INVALID_RANGE_BOUND	as a value	A range (0:3) whose bounds are not plain numbers.
NON_INTEGER_RANGE_BOUND	as a value	A range whose bounds are not whole numbers (0.5:3).
DESCENDING_RANGE	as a value	A range whose first bound is above its second (5:1). The message names each bound as written, with the number it came to, and suggests the other order.
RANGE_BOUND_GROUP_MALFORMED	thrown	A number in a call written like a grouped range bound whose group is not three digits (sum(1,0000:1), sum(1,00:1)): refused by the lexer, since it is neither one bound nor plainly two arguments. The message says a space after the comma gives two.
RANGE_BEFORE_ANOTHER_ARGUMENT	either	A whole-number colon pair no clock reads, written as the first of several arguments to sum, total, prod, map or reduce (sum(100:200, 50)): a range is read only as the last argument. Refused by the normaliser; the message says where the range goes.
LIST_ROUNDING_NON_NUMERIC	as a value	A list rounded (to 2 dp, to 3 sf, round, ceil, floor) that holds a cell with no number to round: a true or false, or a formula with an unknown.
LIST_CONVERSION_UNSUPPORTED	as a value	A list of several numbers written as one: in scientific notation, as a fraction or a percentage, or in hex, binary or octal ([1234, 5678] as sci). Each value is converted on its own.
LIST_ARGUMENT_UNSUPPORTED	as a value	A list of several numbers given to a builtin that reads each argument as one number and has no answer for each cell (gcd([4, 6], 2), root(3, [8, 27]), atan2([1, 2], 1), isprime([2, 4])). The message points at map.
LIST_CELL_UNSUPPORTED	as a value	A list given to a function of one number that is worked out for each cell (sqrt, sin, ln, fact), or added to or taken from a percentage ([true, 2] + 10%), when a cell is not a number (a true or false, a formula with an unknown), when a cell has no real answer (sqrt([4, -9])), or when the answers come in different units.
LIST_PERCENTAGE_UNSUPPORTED	as a value	A percentage written before a plain list with + or - (10% + [100, 200]), or a percentage as a cell of a plain list ([10%, 20%], map(x%, [10, 20])). A list holds plain numbers, so it would keep the percentage as its fraction and add 0.1 where 10% was meant; the message gives the forms that work, [100, 200] + 10% or the fractions [0.1, 0.2].
LIST_CONDITION_UNSUPPORTED	as a value	A list as the condition of an if (if [1, 2] > 0 then 1 else 2), where one true or false is needed. A list compared with a value answers once per cell, so the message points at one cell (v[0] > 5) or at map to choose for each cell.
COLLECTION_TOO_LARGE	as a value	A list or range with more elements than vm.maxCollectionSize allows. A safety limit; the host may raise it.
MATRIX_CELL_NON_NUMERIC	as a value	A list cell that is not a number or a quantity: a list inside a list, text, a date.
MATRIX_CELL_UNITS_DIFFER	as a value	A list whose cells are quantities of different measures ([1 km, 2 kg]), or money in two currencies with no rate between them: a list holds one unit.
MATRIX_CELL_NO_UNIT	as a value	A list with a unit given a cell that has no amount in it: a true or false, a percentage or a formula beside a quantity ([true, 1 km]).
MATRIX_UNIT_OPERATION_UNSUPPORTED	as a value	A list with a unit in an operation its cells cannot take one by one: multiplied by another quantity, a number divided by it, or a percentage added.
MATRIX_UNIT_ALGEBRA	as a value	Matrix algebra on a list with a unit (det([1 km, 2 km; 3 km, 4 km])): a determinant, an inverse, a matrix product or power, or a dot product.
DIMENSION_MISMATCH	as a value	Two matrices of shapes that do not fit the operation: added with different shapes, or multiplied where the columns of the first are not the rows of the second.
MATRIX_INDEX_NOT_A_MATRIX	as a value	[...] indexing or slicing applied to something that is not a matrix.
MATRIX_INDEX_OUT_OF_BOUNDS	as a value	An index or a slice past the edge of the matrix.
INVALID_MATRIX_SLICE_BOUND	as a value	A matrix slice whose bounds are not ranges.
DETERMINANT_REQUIRES_SQUARE_MATRIX	as a value	det of a matrix that is not square.
INVERSE_REQUIRES_SQUARE_MATRIX	as a value	inv of a matrix that is not square.
SINGULAR_MATRIX	as a value	inv of a matrix with no inverse: a zero, or nearly zero, pivot.
MATRIX_POWER_REQUIRES_SQUARE_MATRIX	as a value	A matrix raised to a power that is not square.
MATRIX_POWER_REQUIRES_WHOLE_EXPONENT	as a value	A matrix raised to a power that is not a whole number of 0 or more. ^-1 is the inverse and ^T the transpose.
MATRIX_POWER_UNSUPPORTED	as a value	A matrix used as an exponent, or ^ between a matrix and something with no matrix reading.
SYMBOLIC_INVERSE_DIMENSION_LIMIT	as a value	A symbolic matrix inverse larger than the size the symbolic elimination handles.
SYMBOLIC_SINGULAR_OR_UNSUPPORTED_PIVOT	as a value	A symbolic matrix inverse that meets a zero pivot, which the elimination does not reorder around.
MAP_REDUCE_REQUIRES_COLLECTION	as a value	map, reduce, sum or prod over something that is not a list or a range (sum(5)); the message names the word typed.
MAP_COLLECTION_LENGTH_MISMATCH	as a value	map over several lists of different lengths.
REDUCE_EMPTY_COLLECTION	as a value	reduce over an empty list with no starting value.

Reading other lines

Code	Arrives	When it arises
LINE_REF_NO_DOCUMENT	as a value	A line reference, total above or another cross-line form evaluated with no document, as evaluateExpression is. Evaluate the line in a document instead.
LINE_NOT_YET_EVALUATED	as a value	A reference to a line below the one reading it, or past the end of the document, which has no answer yet.
LINE_RESULT_ERROR	as a value	A reference to a line whose own answer is an error. The referenced line is the one to fix.
LINE_RESULT_PENDING	as a value	A reference to a line still waiting on live data. It resolves when the data arrives.
LINE_FAILED	either	A line read by another line in the batch pass, when it threw and no code was kept for it. A fallback: the code the line threw is used where there is one.

Solving equations for a matrix

Code	Arrives	When it arises
EQUATION_FACTOR_UNDEFINED	as a value	A matrix equation (A * x = b) naming a factor no line defines yet.
EQUATION_FACTOR_NOT_MATRIX	as a value	A matrix equation whose factor is not a matrix.
EQUATION_RHS_NOT_MATRIX	as a value	A matrix equation whose right-hand side is not a matrix.
EQUATION_SEVERAL_UNKNOWNS	thrown	An equation on a line of its own with two or more unknowns, as in (salary / 12) * rate / 100 = net. An equation line is solved for its one unknown, so the message says to give the others values above it or to name one with solve.

Goal seek, as the engine runs it

Code	Arrives	When it arises
GOAL_SEEK_NO_DOCUMENT	as a value	Goal seek with no document to re-run: the single-expression entry point, or the batch pass, which evaluates each line once. evaluateDocument and a live editor solve it.
GOAL_SEEK_NESTED	as a value	Goal seek run from inside another goal seek’s re-run, or targeting its own line. Refused, since the re-runs would compound.
GOAL_SEEK_LINE_NOT_READY	as a value	Goal seek targeting a line with no evaluated expression: below it, past the end, or prose.
GOAL_SEEK_TARGET_IS_DEFINITION	as a value	Goal seek targeting the line that defines a variable, which a re-run would overwrite. The message says to target the line that uses it.
GOAL_SEEK_ASYNC_UNSUPPORTED	as a value	Goal seek targeting a line that depends on live data, which a re-run cannot fetch.
GOAL_SEEK_TARGET_ERROR	as a value	Goal seek whose target line failed while it was being re-run. The message is the line’s own.

What-if and sweeps, re-running the document

Code	Arrives	When it arises
WHAT_IF_LINE_OUT_OF_RANGE	as a value	A what-if or a sweep naming a line the document does not have.
WHAT_IF_NESTED	as a value	A what-if or a sweep run from inside another one’s re-run of the document.
WHAT_IF_IN_GOAL_SEEK	as a value	Goal seek targeting a line that holds a what-if or a sweep, whose every probe would re-run the document again.
WHAT_IF_TARGET_ERROR	as a value	A what-if whose target line has no answer with the inputs given. The message is the line’s own.
WHAT_IF_TARGET_NOT_A_CALCULATION	as a value	A what-if targeting prose, a heading or a blank line, which has no answer to work out again.
WHAT_IF_TARGET_HAS_SEVERAL_ANSWERS	as a value	A what-if targeting a line with several inline answers, so there is no one answer to give.
WHAT_IF_LIVE_DATA	as a value	A what-if targeting a line that waits on live data, which a re-run does not fetch.

Live data

Code	Arrives	When it arises
ASYNC_RESOLVER_FAILED	as a value	A live value that failed to fetch several times in a row, reported rather than retried again. Editing the line tries again.
SETTLE_TIMEOUT	thrown	await engine.settle({ timeoutMs }) reached its deadline with live values still being fetched. Rejected rather than resolved, so a caller is never handed a Pending line as if it were settled; the context carries how many were in flight. Recoverable: the lines stay Pending and settle when their fetches land.
SETTLE_TIMEOUT_INVALID	thrown	engine.settle was given a timeoutMs that is not a finite number of zero or more (a negative, NaN, an infinity, text). Rejected, since it is the host’s argument that is wrong.

Per-pass budgets

Code	Arrives	When it arises
PASS_WORK_BUDGET_EXCEEDED	as a value	A document pass whose cross-line forms together re-ran more lines than vm.maxLineRunsPerPass allows. The line that crossed the budget is refused by name; the host may raise it.
DOCUMENT_ELEMENT_LIMIT_EXCEEDED	as a value	A document whose answers together keep more elements than vm.maxRetainedElements allows. The line that crossed it is refused, and a name it assigned is let go.

Fallbacks for a thrown value that is not an EngineError

Code	Arrives	When it arises
UNEXPECTED_ERROR	thrown	Something other than an EngineError was thrown and normalised. Worth reporting: it is an engine or package fault rather than the reader’s line.
UNKNOWN_ERROR	thrown	A thrown value that was not an Error at all, normalised. Worth reporting, as UNEXPECTED_ERROR is.

DatetimeZoneErrorCodes

In the package as ERROR_CODE_CATALOGUES.DatetimeZoneErrorCodes.

Code	Arrives	When it arises
TIME_ZONE_OFFSET_OUT_OF_RANGE	either	2026-04-03 in UTC+25, time in UTC-5:60: a signed offset after UTC or GMT that no clock keeps (outside UTC-12 to UTC+14, sixty minutes or more, a fraction, or a time of day). An Error value from the VM’s in <zone> branch, and a parse error from the time package’s zone forms, each as that form refuses an unknown zone; both read the offset with calendar/UtcOffset.ts’s tryReadUtcOffset (#730).
DATETIME_ZONE_UNKNOWN	as a value	A date converted in <name> where the name is neither a time zone the engine knows nor a unit, as in 2026-04-03 in Atlantis. The reader checks the zone’s spelling.
DATETIME_NOT_CONVERTIBLE	as a value	A date converted in <unit> where the name is a real unit that a date has no reading in, as in 2026-04-03 in furlongs. Separate from DATETIME_ZONE_UNKNOWN, since the fix is different.
DATE_ZONE_UNKNOWN	thrown	dateCalendarInZone given a zone this runtime cannot compute in, as in "Europe/Atlantis". Raised when the host builds the calendar, not per line.
DATE_WEEKDAY_INVALID	thrown	date: { weekend: ["fri"] }: date.weekend or date.firstDayOfWeek named something that is not a day of the week. Raised at construction, because a weekend quietly ignored is every working-day answer quietly wrong (#702).

CurrencyErrorCodes

In the package as ERROR_CODE_CATALOGUES.CurrencyErrorCodes.

Code	Arrives	When it arises
CURRENCY_API_ERROR	thrown	Frankfurter’s rates endpoint returned a non-OK HTTP status.
UNKNOWN_CURRENCY_CODE	thrown	A requested currency/crypto code isn’t in the fetched rate table, an unrecognized code, not an API failure.
CRYPTO_PRICE_API_ERROR	thrown	CoinGecko’s simple-price endpoint returned a non-OK HTTP status.

HistoricalCurrencyErrorCodes

In the package as ERROR_CODE_CATALOGUES.HistoricalCurrencyErrorCodes.

Code	Arrives	When it arises
HISTORICAL_RATES_NOT_CONFIGURED	as a value	The host switched historical rates off (historicalRateProvider: null), so on <date> conversions cannot be answered. NOT a fall back to today’s rate.
HISTORICAL_RATE_QUERY_FAILED	either	The provider threw, timed out, or answered with something that is not a rate, for one pair/date. Transient, evicted after a cooldown so a retry can happen.
HISTORICAL_RATE_DATE_OUT_OF_RANGE	thrown	A dated conversion for a day the built-in Frankfurter rates do not cover: before 4 January 1999 (the ECB reference rates’ first day) or after today.
HISTORICAL_RATE_UNSUPPORTED_CURRENCY	thrown	A dated conversion for a currency the built-in Frankfurter rates do not quote: a cryptocurrency, or a code the ECB publishes no rate for.
HISTORICAL_RATE_NOT_PREFLIGHTED	as a value	The VM reached the conversion before preflight cached its rate, a “shouldn’t happen” invariant break, not a user error.
HISTORICAL_CURRENCY_INVALID_OPERAND	as a value	The amount being converted was not a currency Value (bad bytecode, or a non-currency left operand).

QueryResolverErrorCodePatterns

In the package as ERROR_CODE_CATALOGUES.QueryResolverErrorCodePatterns.

Code	Arrives	When it arises
<NAMESPACE>_QUERY_FAILED	as a value	A live value whose fetch failed (the provider threw, or the network did). The line is refused rather than answered with a stale or made-up value; a later evaluation retries after the cooldown.
<NAMESPACE>_NOT_PREFLIGHTED	as a value	A live value read before its fetch was started, which the engine’s preflight makes unreachable. Worth reporting if a host sees it.

SnapshotErrorCodes

In the package as ERROR_CODE_CATALOGUES.SnapshotErrorCodes.

Code	Arrives	When it arises
SNAPSHOT_VERSION_MISMATCH	thrown	The object handed to fromJSON is not a snapshot at all, or its version does not match this engine’s reader.
SNAPSHOT_MALFORMED	thrown	A snapshot with the right envelope but internally inconsistent contents (a bad number sentinel, a missing field).
SNAPSHOT_UNSUPPORTED_VALUE	thrown	A value the snapshot format cannot yet represent (a symbolic expression or matrix cell, a colour, a split, a chart, an IP subnet). toJSON catches it and leaves the value out.
SNAPSHOT_PACKAGE_MISSING	thrown	The snapshot calls a plugin function that no package registered on the restoring engine provides. Refused rather than restored, since the call would run whatever sits at its old index (#658).

DefineFunctionErrorCodes

In the package as ERROR_CODE_CATALOGUES.DefineFunctionErrorCodes.

Code	Arrives	When it arises
DEFINE_FUNCTION_INVALID_NAME	thrown	The spec’s name is not a single identifier. Thrown by defineFunction, before any engine sees it.
DEFINE_FUNCTION_INVALID_SPEC	thrown	The spec is otherwise malformed (bad args, unsupported type, missing call). Thrown by defineFunction.
DEFINE_FUNCTION_ARITY_MISMATCH	thrown	The call site passed the wrong number of arguments. Raised at evaluation time.
DEFINE_FUNCTION_ARGUMENT_TYPE	thrown	An argument was the wrong value type. Raised at evaluation time.
DEFINE_FUNCTION_RETURN_TYPE	thrown	The call implementation returned a value that did not match returns. Raised at evaluation time, an authoring bug rather than a user one.

WorkerErrorCodes

In the package as ERROR_CODE_CATALOGUES.WorkerErrorCodes.

Code	Arrives	When it arises
WORKER_CANCELLED	thrown	The caller aborted the request through its AbortSignal.
WORKER_TERMINATED	thrown	The worker engine was torn down while a request was still in flight.
WORKER_TRANSPORT_FAILED	thrown	The transport failed or the worker exited before answering.
WORKER_UNKNOWN_METHOD	thrown	A request named a method the runtime does not expose.
WORKER_NOT_INITIALISED	thrown	A request arrived before the runtime finished building its engine.
WORKER_UNKNOWN_PACKAGE	thrown	An init named a package the runtime could not resolve.
WORKER_ARGUMENT_NOT_CLONEABLE	thrown	A call’s arguments could not be copied across the boundary (a function, a symbol, an object postMessage refuses). Rejected main-side, before anything is sent.

Category tags

TagsErrorCodes

In the package as ERROR_CODE_CATALOGUES.TagsErrorCodes.

Code	Arrives	When it arises
TAG_NO_DOCUMENT	as a value	A tag total evaluated with no document to read tagged lines from.
TAG_EMPTY	as a value	A tag total or a breakdown with no lines carrying the tag, or no tagged lines at all.
TAG_NON_NUMERIC	as a value	A tagged line that is not a number or a quantity.
TAG_BREAKDOWN_NO_WHOLE	as a value	A breakdown whose tagged lines add up to zero, so no tag has a share.

Chart

ChartErrorCodes

In the package as ERROR_CODE_CATALOGUES.ChartErrorCodes.

Code	Arrives	When it arises
PLOT_EXPR_MUST_BE_SYNCHRONOUS	thrown	A plot whose expression reaches live data (weather, stocks, a currency rate), which a plot cannot wait for at every point.
SPARKLINE_NOT_A_SERIES	as a value	as sparkline given something other than a list or a range of at least two numbers.

Colour

ColourErrorCodes

In the package as ERROR_CODE_CATALOGUES.ColourErrorCodes.

Code	Arrives	When it arises
COLOUR_INVALID	as a value	A string was not a hex colour or a known CSS colour name.
COLOUR_EXPECTED_COLOUR	as a value	A function expected a colour argument and got something else.
COLOUR_BAD_ARGUMENTS	as a value	A function was called with the wrong number or type of arguments.
UNKNOWN_COLOUR_FUNCTION	thrown	A colour call (rgb(...), hsl(...)) by a name the colour package does not have.

Conditionals and checks

ConditionalsErrorCodes

In the package as ERROR_CODE_CATALOGUES.ConditionalsErrorCodes.

Code	Arrives	When it arises
CHECK_EXPECTED_COMPARISON	either	A check whose statement is not a comparison. The message shows the forms a check takes.
CHECK_FAILED	as a value	A check whose comparison does not hold. The message says by how much; a host counts these through ParsingResult.checks.
CHECK_INCOMPARABLE	as a value	A check between two values that cannot be compared: text with <, or quantities of different measures.
CHECK_JOIN_UNSUPPORTED	thrown	A check whose comparisons are joined by something other than and: or, a bitwise operator, or a comparison after a within margin. The message says to join them with and or to bracket a side.
NOT_NEEDS_BOOLEAN	as a value	not or a prefix ! before a value that is not true or false (not 5, !"yes"). The message names what the value is.

Constants

ConstantsErrorCodes

In the package as ERROR_CODE_CATALOGUES.ConstantsErrorCodes.

Code	Arrives	When it arises
UNKNOWN_CONSTANT	as a value	A physical constant asked for by a name the table does not have.

Converters and rounding

ConvertersErrorCodes

In the package as ERROR_CODE_CATALOGUES.ConvertersErrorCodes.

Code	Arrives	When it arises
AS_CONVERTER_EXPECTED_NAME	thrown	as followed by something that is not a converter name, as in 1 as as.
AS_CONVERTER_EXPECTED_NUMBER	as a value	A number notation (as engineering, as compact) given something that is not a number or a quantity.
AS_CONVERTER_UNSUPPORTED_BASE	thrown	as base N for a base the engine cannot write numbers in. The message lists the bases it can.
INVALID_DECIMAL_PLACES	thrown	to N dp with a place count outside 0 to 100.
INVALID_SIGNIFICANT_FIGURES	thrown	to N sf with a count that is not a whole number from 1 to 17.
INVALID_ROUNDING_INCREMENT	thrown	to nearest ... followed by something that is not a positive number or a word such as ten or hundred.

Cooking

CookingErrorCodes

In the package as ERROR_CODE_CATALOGUES.CookingErrorCodes.

Code	Arrives	When it arises
GAS_MARK_EXPECTED_TEMPERATURE	as a value	as gas mark was given something that is not an oven temperature.
GAS_MARK_OFF_THE_DIAL	as a value	An oven temperature that no gas mark stands for, hotter or colder than the dial goes.
GAS_MARK_UNKNOWN	as a value	A dial setting the table does not have, such as gas mark 12.
SERVINGS_NOT_POSITIVE	as a value	A serving count that cannot scale a recipe, such as zero.

Crypto

CryptoErrorCodes

In the package as ERROR_CODE_CATALOGUES.CryptoErrorCodes.

Code	Arrives	When it arises
CRYPTO_NOT_CONFIGURED	as a value	A crypto price asked for on an engine whose crypto package was created without a fetchPrice. The host supplies one through createCryptoPackage.

Dates

DateFormErrorCodes

In the package as ERROR_CODE_CATALOGUES.DateFormErrorCodes.

Code	Arrives	When it arises
DATE_EXPECTED	as a value	A date form (2nd Tuesday of, age of) given something that is not a date, as in age of 5.
DATE_FIELD_EXPECTED_DATE	as a value	A question asked of a date (day of the week on, week number of) given something that is not a date.
DATE_OUT_OF_RANGE	as a value	A timestamp outside the dates the engine can hold, about 273,000 years either side of 1970.
AS_ISO8601_NEEDS_DATE	as a value	as iso8601 given something that is not a date, a Unix timestamp or ISO 8601 text.
AS_ISO8601_DURATION_TOO_LONG	as a value	as iso8601 given a length of time too large for its parts to be written with exact digits, as in 1e300 seconds as iso8601.
INVALID_ISO8601_STRING	as a value	Text given as an ISO 8601 date or time that does not read as one.
INVALID_WEEKDAY	as a value	A weekday given as a number that is not a day of the week.
MISSING_WEEKDAY	thrown	next or last with no day of the week after it.
NTH_WEEKDAY_OUT_OF_RANGE	as a value	An ordinal weekday the month does not have, such as the fifth Monday of a month with four.
DAYS_IN_EXPECTED_PERIOD	thrown	days in followed by something that is not a month, a quarter or a year.
WORKDAYS_IN_EXPECTED_DURATION	as a value	workdays in given a quantity that is not a length of time.
WORKDAYS_UNTIL_UNSUPPORTED	thrown	workdays until or workdays since, which are not counted on the calendar. The message points at workdays between.
AS_DATE_NEEDS_TIMESTAMP	as a value	as date given a value that is neither a Unix timestamp, ISO 8601 text nor a date.
AS_TIMESTAMP_NEEDS_DATE	as a value	as timestamp given a value that is neither a date, ISO 8601 text nor a Unix timestamp.
AS_TIME_NEEDS_DATE	as a value	as time given something that is not a date, as in 5 as time. A number has no time of day of its own, so it is read as a date first: 1710000000 as date as time.
PERIOD_EXPECTED	thrown	start of or end of followed by something that is not a week, a month or a year.
WEEKDAY_ALONE	thrown	A day of the week alone on a line, which is read as a heading. The message points at this friday or next friday for the date.

DatetimeErrorCodes

In the package as ERROR_CODE_CATALOGUES.DatetimeErrorCodes.

Code	Arrives	When it arises
DATE_INPUT_LOCALE_INVALID	thrown	date.inputLocale is not a BCP-47 locale tag ("en_US" with an underscore is the usual mistake). Raised at engine construction, because a locale that is silently ignored is a date order that is silently wrong.
DATE_ORDER_MISMATCH	either	A date-shaped run the resolved order cannot read, which another supported order can (12/25/2026 on a day-first engine), or a year-last run on a year-first engine, which has no day and month roles to apply to it. The message names the order actually used, the group that broke, the reading that would work, and the two ways out. A recoverable Error VALUE, never a throw, and suppressed by date.onAmbiguous: 'arithmetic'.
DATE_NOT_A_CALENDAR_DAY	either	A run whose shape is unmistakably a date attempt and which names no real day under any reading: 31/04/2026, 29/02/2026, 13/13/2026, 2026-02-29, 2026-13-01. Separate from DATE_ORDER_MISMATCH because no change of order fixes it, so the message must not suggest one.

Derived units

DerivedUnitsErrorCodes

In the package as ERROR_CODE_CATALOGUES.DerivedUnitsErrorCodes.

Code	Arrives	When it arises
AS_UNIT_EXPECTED_QUANTITY	as a value	as <unit> given a plain number or something else with no unit.
AS_UNIT_INCOMPATIBLE	as a value	as <unit> given a quantity that does not measure what the unit does.

Encoding

EncodingErrorCodes

In the package as ERROR_CODE_CATALOGUES.EncodingErrorCodes.

Code	Arrives	When it arises
ENCODING_EXPECTED_TEXT	as a value	An encoding form given something that is not text in quotes.
ENCODING_DECODE_FAILED	as a value	Text that does not decode in the encoding named: not valid base64, not a JSON Web Token, not a query string.
UNKNOWN_ENCODING	as a value	from <name> naming an encoding the package does not know. The message lists the ones it does.

Finance

FinanceErrorCodes

In the package as ERROR_CODE_CATALOGUES.FinanceErrorCodes.

Code	Arrives	When it arises
CASH_FLOW_ARGUMENT_COUNT	as a value	A cash-flow form given no flows, or npv given flows with no rate.
CASH_FLOW_EXPECTED_AMOUNT	as a value	A cash flow that is not a finite amount of money or a plain number, or flows given both one by one and as a list.
CASH_FLOW_MISSING_RATE	thrown	npv of ... with no at <rate> after the flows.
CASH_FLOW_TOO_FEW	as a value	A cash-flow form given fewer than two flows: an outlay and a return are the least it reads.
CASH_FLOW_OUT_OF_RANGE	as a value	A net present value beyond the range of a number at the rate given.
IRR_NO_SIGN_CHANGE	as a value	irr of flows that never change sign (all money out, or all in), so no rate makes their value zero.
IRR_NONE	as a value	irr of flows no rate above -100% brings to zero.
IRR_NOT_UNIQUE	as a value	irr of flows with several internal rates of return. The message lists them rather than choosing one.
IRR_UNRESOLVED	as a value	irr of flows whose rates are too close together to tell apart.
PAYBACK_NO_OUTLAY	as a value	payback of flows whose running total is never below zero, so there is nothing to pay back.
PAYBACK_NEVER	as a value	payback of flows that never recover the outlay. The message says how far short the total ends.
INFLATION_EXPECTED_USD	either	<amount> in <year> dollars of an amount in another currency that has its own index: the phrase asks for dollars.
INFLATION_EXPECTED_CURRENCY	either	<amount> in <year> pounds or in <year> euros of an amount in another currency that has its own index: the phrase asks for that currency.
INFLATION_NO_INDEX	as a value	An inflation adjustment of an amount no bundled price index measures: a currency without one, a quantity that is not money, or a bare number.
INFLATION_EXPECTED_FROM_OR_IN	thrown	what is <amount> followed by neither from <year> nor in <year> worth in <year>, as in what is $300 and $50 from 2003.
INFLATION_EXPECTED_YEAR	as a value	The year of an inflation question that is not a plain whole number: money, a quantity, a date or a fraction, as in what is $100 from 1990.5.
INFLATION_EXPECTED_INFLATION_WORD	thrown	assuming <rate>% not followed by the word inflation.
SAVINGS_GOAL_SYNTAX	thrown	how much per month to reach <target> followed by neither in nor over and the time the saving runs for.
UNKNOWN_COMPOUNDING_INTERVAL	thrown	compounding <interval> naming an interval the package does not know. The message lists the ones it does.

RecurringScheduleErrorCodes

In the package as ERROR_CODE_CATALOGUES.RecurringScheduleErrorCodes.

Code	Arrives	When it arises
RECURRING_INTERVAL_NOT_POSITIVE	thrown	every 0 weeks and the like: the interval a payment repeats on has to be a positive count, or the number of payments is undefined.

Geometry

GeometryErrorCodes

In the package as ERROR_CODE_CATALOGUES.GeometryErrorCodes.

Code	Arrives	When it arises
GEOMETRY_EXPECTED_SHAPE	thrown	A shape measure (area of) followed by something that is not a shape. The message lists the shapes.
GEOMETRY_ERROR	as a value	A shape given a dimension that is not a length or a number, or a set of dimensions that make no shape.

Goal seek

GoalSeekErrorCodes

In the package as ERROR_CODE_CATALOGUES.GoalSeekErrorCodes.

Code	Arrives	When it arises
GOAL_SEEK_SYNTAX	thrown	A goal seek not written as solve line N for <name> = <target>. The message shows the form.
GOAL_SEEK_REQUIRES_VARIABLE_NAME	thrown	A goal seek with no name to vary after for.
GOAL_SEEK_TARGET_NOT_NUMERIC	as a value	A goal seek whose target is not a finite number, or whose target line does not give a number for a value tried.
GOAL_SEEK_TARGET_UNIT_MISMATCH	as a value	A goal seek’s target in a unit that cannot be compared with the target line’s answer: another measure, or money in another currency. The reader writes the target in the line’s unit (#835).
GOAL_SEEK_VARIABLE_NOT_USED	as a value	A goal seek varying a name its target line does not read, which could never move the answer.
GOAL_SEEK_NON_FINITE	as a value	A goal seek whose target line gives no finite value for any input tried across the range, as 2^x does not far out and 1/x does not at zero. A value that is not finite for some inputs is a gap in the search, not this (#739).
GOAL_SEEK_NO_SOLUTION	as a value	A goal seek over a range in which the target line stays on one side of the target wherever it could be worked out, or whose exact answers all lie outside a stated range. The message names the range searched.
GOAL_SEEK_RANGE_INVALID	as a value	A goal seek’s between <low> and <high> whose ends are not two different finite numbers in the unknown’s measure (#739).
GOAL_SEEK_SEVERAL_SOLUTIONS	as a value	A goal seek whose unknown carries a unit and whose line meets the target at several inputs. A list cannot carry the unit, so each value is named and the reader chooses with a range (#739).
GOAL_SEEK_TOO_MANY_SOLUTIONS	as a value	A goal seek whose line meets the target at more inputs than a list of answers should hold, as a line built on sin or cos does (#739).
GOAL_SEEK_DID_NOT_CONVERGE	as a value	A goal seek that did not reach the target within its steps, or narrowed to a point where the line jumps across it.

Hash

HashErrorCodes

In the package as ERROR_CODE_CATALOGUES.HashErrorCodes.

Code	Arrives	When it arises
HASH_EXPECTED_TEXT	as a value	A hash function (sha256(...)) given something that is not text in quotes.

Health

HealthErrorCodes

In the package as ERROR_CODE_CATALOGUES.HealthErrorCodes.

Code	Arrives	When it arises
HEALTH_BAD_INPUT	as a value	A health function given an argument of the wrong kind, such as a weight where a height goes. The message shows the call.

Knowledge

KnowledgeErrorCodes

In the package as ERROR_CODE_CATALOGUES.KnowledgeErrorCodes.

Code	Arrives	When it arises
KNOWLEDGE_NOT_CONFIGURED	as a value	A knowledge question asked on an engine whose knowledge package was created without an answerQuery. The host supplies one through createKnowledgePackage.

Lines, ranges and sections

LinesErrorCodes

In the package as ERROR_CODE_CATALOGUES.LinesErrorCodes.

Code	Arrives	When it arises
LINE_RANGE_NON_NUMERIC	as a value	A line range or an above aggregate reaching a line that is not a number or a quantity.
LINE_RANGE_EMPTY	as a value	A line range or an above aggregate with no figures in it: every line blank, a heading, or the top of the document.
LINE_REFERENCE_DELETED	as a value	A reference to a line that has since been deleted. An editor that keeps references through edits writes it as line deleted.
SECTION_NO_DOCUMENT	as a value	A section total evaluated with no document to read headings from.
SECTION_NOT_FOUND	as a value	A section total naming a heading the note does not have. The message lists the headings it has.
SECTION_AMBIGUOUS	as a value	A section total naming a heading two or more headings share.
SECTION_EMPTY	as a value	A section with no figures under its heading.
INPUTS_OF_SYNTAX	thrown	inputs of not followed by a line reference, as in inputs of line 4.
TRACE_CYCLE	as a value	inputs of a line that reads its own answer, directly or round a loop of lines.
TRACE_FORWARD_REFERENCE	as a value	inputs of a line that reads a line below it, whose order of working cannot be traced.

Map and reduce

MapReduceErrorCodes

In the package as ERROR_CODE_CATALOGUES.MapReduceErrorCodes.

Code	Arrives	When it arises
MAP_REDUCE_EXPECTED_COLLECTION_NAME	thrown	A map over named collections (map(x + y, x = [1, 2], y = [3, 4])) with one that has no name before its =.
MAP_REDUCE_TRANSFORM_MUST_BE_SYNCHRONOUS	thrown	A map, reduce, sum or prod whose expression reaches live data, which it cannot wait for once per element.

Maths phrases

MathPhrasesErrorCodes

In the package as ERROR_CODE_CATALOGUES.MathPhrasesErrorCodes.

Code	Arrives	When it arises
AGGREGATE_CALL_EMPTY	thrown	An aggregate call with nothing inside, as in mean(), refused rather than answered 0.
AGGREGATE_CALL_RANGE	thrown	An aggregate call whose only argument is written like a range (average(1:3), mean(1:3), median(1:3)), which outside sum (and its synonym total), prod, map and reduce is a clock time.
AGGREGATE_NAME_RESERVED	thrown	A function of the reader’s own defined under an aggregate’s name (mean, median, stdev), which a call would never reach.
CLAMP_EXPECTED_BETWEEN_OR_FROM	thrown	clamp <value> followed by neither between nor from.
REMAINDER_EXPECTED_DIVIDED_BY	thrown	remainder of <a> not followed by divided by or /.
ROOT_EXPECTED_OF	thrown	root <n> not followed by of.
LOG_EXPECTED_BASE	thrown	log <n> not followed by base.
PROPORTION_EXPECTED_WHAT	thrown	A proportion (5 km is to 500 m as 5 cm is to what) missing its final what.
WEIGHTED_AVERAGE_MISSING_WEIGHT	thrown	A weighted average with a value that has no at <weight> after it.

Matrix

MatrixErrorCodes

In the package as ERROR_CODE_CATALOGUES.MatrixErrorCodes.

Code	Arrives	When it arises
EMPTY_MATRIX_LITERAL	thrown	A matrix written as [], which has no shape.
RAGGED_MATRIX_LITERAL	thrown	A matrix whose rows have different numbers of columns. The message names the row.
INVALID_MATRIX_SLICE_ARITY	thrown	A matrix slice with other than two ranges, one for the rows and one for the columns.

Networking

IpErrorCodes

In the package as ERROR_CODE_CATALOGUES.IpErrorCodes.

Code	Arrives	When it arises
IP_EXPECTED	as a value	A networking form given something that is not an IP address or a subnet.
IP_NO_PREFIX	as a value	hosts in or netmask of given an address with no prefix length, as in /24.
IP_NEEDS_ADDRESS_AND_PREFIX	as a value	broadcast of, network of or last address of given something without both an address and a prefix.
IP_EXPECTED_ADDRESS	as a value	<address> in <subnet> with no address on the left.
IP_EXPECTED_BLOCK	as a value	<address> in <subnet> with no subnet on the right.
IP_PREFIX_OUT_OF_RANGE	as a value	A prefix no address has (netmask of /200, 2001:db8::/129): IPv4 prefixes run from 0 to 32 and IPv6 prefixes from 0 to 128.
IP_FAMILY_MISMATCH	as a value	<address> in <subnet> with an IPv4 address and an IPv6 subnet, or the other way round.
IPV6_NO_BROADCAST	as a value	broadcast of an IPv6 block: IPv6 has no broadcast address, and last address of gives the block’s last one.

Numerals

NumeralsErrorCodes

In the package as ERROR_CODE_CATALOGUES.NumeralsErrorCodes.

Code	Arrives	When it arises
NUMERAL_EXPECTED_NUMBER	as a value	A numeral form (as roman, as words) given something that is not a number.
NUMERAL_OUT_OF_RANGE	as a value	A number the numeral form cannot write: Roman numerals cover 1 to 3,999, and a number past the largest spelled one has no words.
NUMERAL_EXPECTED_TEXT	as a value	from roman given something that is not text in quotes.
NUMERAL_INVALID_ROMAN	as a value	from roman given text that is not a valid Roman numeral.

Payroll

PayrollErrorCodes

In the package as ERROR_CODE_CATALOGUES.PayrollErrorCodes.

Code	Arrives	When it arises
PAYROLL_EXPECTED_GBP	as a value	The banded forms were given something other than a pound salary.
PAYROLL_EXPECTED_RATE	as a value	A stated tax rate was not a rate a take-home can be worked out from.
PAYROLL_UNKNOWN_LOAN_PLAN	either	with student loan with no plan, or a plan that does not exist (with plan 3 student loan).
PAYROLL_CONFLICTING_CASE	either	Two places, two pensions, a plan named twice, or two undergraduate plans on one take-home line.
PAYROLL_EXPECTED_PENSION_RATE	either	with 150% pension: a pension contribution that is not a percentage between 0 and 100.
PAYROLL_NEGATIVE_SALARY	as a value	-£50,000 after tax or hourly for -£50,000: a salary below zero, which no one is paid.

Percentage

PercentageErrorCodes

In the package as ERROR_CODE_CATALOGUES.PercentageErrorCodes.

Code	Arrives	When it arises
IS_WHAT_EXPECTED_PERCENT	thrown	<a> is what not followed by % or percent.
IS_WHAT_EXPECTED_PREPOSITION	thrown	<a> is <n>% not followed by of what, off what or on what.
IS_WHAT_EXPECTED_WORD	thrown	A percentage phrase missing one of its words part-way through. The message names the word.
PERCENT_CHANGE_EXPECTED_TO	thrown	percent change from <a> not followed by to and the new value.

Places

GeoErrorCodes

In the package as ERROR_CODE_CATALOGUES.GeoErrorCodes.

Code	Arrives	When it arises
GEO_EXPECTED_PLACE	as a value	A distance or bearing was given something that is not a place.
GEO_OUT_OF_RANGE	as a value	A latitude or longitude was outside the globe.
GEO_BAD_ANGLE	as a value	An angle literal’s parts do not make an angle (75 minutes, say).
GEO_NOT_A_PLACE	as a value	Two lettered angles side by side were not one latitude and one longitude.
GEO_NO_BEARING	as a value	The two places have no single direction between them.
GEO_EXPECTED_ANGLE	as a value	as dms was given something that is not an angle or a place.
GEO_EXPECTED_SECOND_PLACE	thrown	A distance or bearing between places with no second place after its to or and.

Random

RandomErrorCodes

In the package as ERROR_CODE_CATALOGUES.RandomErrorCodes.

Code	Arrives	When it arises
RANDOM_EXPECTED_COUNT	as a value	random hex given a count that is not a number of 0 or more.
RANDOM_PICK_EMPTY	as a value	pick with no options to choose from.
RANDOM_SHUFFLE_EXPECTED_LIST	as a value	shuffle given something that is not a single row or column.
RANDOM_SEED_EXPECTED_VALUE	thrown	random seed with nothing after it to seed with.

Ratio

RatioErrorCodes

In the package as ERROR_CODE_CATALOGUES.RatioErrorCodes.

Code	Arrives	When it arises
RATIO_EXPECTED_NUMBERS	as a value	ratio(...) given something that is not a whole number.
RATIO_INVALID	as a value	ratio(...) given fewer than two whole positive numbers.

Screen and image sizes

WebErrorCodes

In the package as ERROR_CODE_CATALOGUES.WebErrorCodes.

Code	Arrives	When it arises
WEB_EXPECTED_PIXELS	as a value	A width or a height was not a whole count of pixels.
DENSITY_EXPECTED_NUMBER	thrown	at and dpi with a word rather than a number of dots per inch between them, as in 4000px at x dpi.
WEB_EXPECTED_PX_OR_REM	as a value	A size measured against a root font size was in neither px nor rem.
WEB_EXPECTED_ROOT_SIZE	as a value	The stated root font size was not a size a rem can be measured against.
WEB_EXPECTED_PIXELS_OR_LENGTH	as a value	A size measured against a density was neither a CSS length nor a physical length.
WEB_EXPECTED_DENSITY	as a value	The stated density was not a number of dots per inch above zero.

Shopping

ShoppingErrorCodes

In the package as ERROR_CODE_CATALOGUES.ShoppingErrorCodes.

Code	Arrives	When it arises
VS_INCOMPARABLE	as a value	<a> vs <b> between two amounts that are not the same kind of thing.

Statistics

StatisticsErrorCodes

In the package as ERROR_CODE_CATALOGUES.StatisticsErrorCodes.

Code	Arrives	When it arises
STAT_ARGUMENT_COUNT	as a value	A statistics function given the wrong number of arguments. The message shows the call.
STAT_EXPECTED_LIST	as a value	A statistic that reads a list given something else, or too short a list.
STAT_EXPECTED_LISTS	as a value	A two-list statistic (correlation, slope) given something other than two lists.
STAT_LENGTH_MISMATCH	as a value	A two-list statistic given lists of different lengths.
STAT_TOO_FEW	as a value	A two-list statistic given fewer than two paired points.
STAT_EMPTY	as a value	A statistic of an empty list.
STAT_EXPECTED_PERCENT	as a value	percentile given no percentage.
STAT_PERCENT_RANGE	as a value	percentile given a percentage outside 0 to 100.
STAT_EXPECTED_VALUE	as a value	A distribution or zscore given something that is not a number where a number goes.
STAT_PROBABILITY_RANGE	as a value	A distribution given a probability outside the range it takes.
STAT_NOT_WHOLE	as a value	A distribution given a count that is not a whole number.
STAT_COUNT_RANGE	as a value	A distribution given a count below zero, or more successes than trials.
STAT_SD_NOT_POSITIVE	as a value	A normal distribution given a standard deviation of zero or less.
STAT_GAMMA_POLE	as a value	gamma at zero or a negative whole number, where it is undefined.
STAT_OVERFLOW	as a value	A distribution or gamma whose answer is beyond the largest number a double can hold.
STAT_NO_CONVERGENCE	as a value	A distribution whose series did not settle on an accurate answer for arguments this large.

Stocks

StocksErrorCodes

In the package as ERROR_CODE_CATALOGUES.StocksErrorCodes.

Code	Arrives	When it arises
STOCKS_NOT_CONFIGURED	as a value	A stock price asked for on an engine whose stocks package was created without a provider. The host supplies one through createStocksPackage.
STOCKS_INVALID_TICKER	thrown	stock(...) given something that is not a ticker symbol.
STOCKS_EXPECTED_ON	thrown	A historical price field (close, open) not followed by on <date>.
STOCKS_EXPECTED_DATE	thrown	on not followed by a date the stocks package reads.
STOCKS_INVALID_DATE	thrown	A date after on that is not a real calendar date, or has no four-digit year.

Symbolic

SymbolicErrorCodes

In the package as ERROR_CODE_CATALOGUES.SymbolicErrorCodes.

Code	Arrives	When it arises
SYMBOLIC_ARGUMENT_MUST_BE_SYNCHRONOUS	thrown	An algebra verb (der, integral, solve) whose expression reaches live data.

Tables

TablesErrorCodes

In the package as ERROR_CODE_CATALOGUES.TablesErrorCodes.

Code	Arrives	When it arises
TABLE_NO_DOCUMENT	as a value	Cross-line table reads need a real document, absent on the single-expression path.
TABLE_NOT_FOUND	as a value	No markdown table was found above the query line.
TABLE_COLUMN_NOT_FOUND	as a value	The named column is not one of the table’s headers.
TABLE_COLUMN_NO_NUMERIC_CELLS	as a value	The column held no number or money cells to aggregate.
TABLE_COLUMN_PERCENT_CELL	as a value	A column summary met a percentage cell, which it does not add to or compare with the figures (#651).
TABLE_COLUMN_AMBIGUOUS	either	A lookup named a column the header carries more than once.
TABLE_ROW_NOT_FOUND	either	No row’s first cell carries the label an exact lookup asked for.
TABLE_ROW_AMBIGUOUS	either	More than one row carries the label, so an exact lookup cannot choose.
TABLE_LOOKUP_KEY_INVALID	either	An exact lookup’s key was neither quoted text nor a plain number.
TABLE_CELL_EMPTY	either	The looked-up cell is empty.
TABLE_CELL_NOT_A_VALUE	either	The looked-up cell is text, not a number, an amount of money or a percentage.
TABLE_BANDS_MALFORMED	either	The table cannot be read as bands: a start that is not a number, starts out of order, a rate that cannot be read.
TABLE_BANDS_NOT_FROM_ZERO	either	A progressive total’s first band does not start at 0, so part of the amount falls in no band.
TABLE_BAND_BELOW_FIRST	either	A band lookup’s amount is below where the first band starts.
TABLE_BAND_AMOUNT_INVALID	either	The amount placed in the bands is not a plain number or money, or is below zero for a progressive total.
TABLE_BAND_UNIT_MISMATCH	either	The amount, the band starts and the rates name currencies that do not go together.
TABLE_COLUMN_NAME_EXPECTED	thrown	A column form (sum of column, column ... for) not followed by a column name in quotes.
TABLE_LOOKUP_FOR_EXPECTED	thrown	A table lookup not followed by for and a row, as in column "cost" for "food".

Text

TextExtractionErrorCodes

In the package as ERROR_CODE_CATALOGUES.TextExtractionErrorCodes.

Code	Arrives	When it arises
TEXT_EXPECTED	as a value	A form was given something other than text where it reads text.
TEXT_ARGUMENT_COUNT	as a value	A call form was given the wrong number of arguments.
TEXT_NO_NUMBERS	as a value	The text has no numbers for an aggregate to work on.
TEXT_NO_AMOUNTS	as a value	The text has no amounts of money for an aggregate to work on.
TEXT_TOO_MANY_NUMBERS	as a value	The text holds more numbers than one read allows.
TEXT_NO_MATCH	as a value	The pattern does not occur in the text.
TEXT_PATTERN_TOO_COSTLY	as a value	Matching took more steps than one call allows.
TEXT_PATTERN_INVALID	either	The pattern is not well formed.
TEXT_PATTERN_UNSUPPORTED	either	The pattern uses a feature the matcher refuses.
TEXT_PATTERN_TOO_LARGE	either	The pattern is past a size limit.
TEXT_NOT_JSON	either	field was given text that is not JSON.
TEXT_FIELD_PATH_INVALID	either	field was given a malformed path.
TEXT_FIELD_NOT_FOUND	either	The path leads nowhere in the JSON.
TEXT_FIELD_NULL	either	The field holds null.
TEXT_FIELD_INEXACT_NUMBER	either	The field holds a whole number too large to read exactly.

Times and time zones

TimeFormErrorCodes

In the package as ERROR_CODE_CATALOGUES.TimeFormErrorCodes.

Code	Arrives	When it arises
TIME_ZONE_EXPECTED_CITY	thrown	time in not followed by a city or a zone.
TIME_ZONE_EXPECTED_IN	thrown	A time in one zone not followed by in <city> for the zone to convert to.
TIME_ZONE_EXPECTED_TARGET	thrown	in not followed by a city or a zone to convert to.
TIME_ZONE_UNKNOWN	thrown	A place named as a time zone that the engine does not know. The message says what it reads: a city, an abbreviation or an offset.
TIME_ZONE_TOO_MANY	thrown	One line naming more time zones than a line takes.
TIME_ZONE_MISSING_DATE	thrown	on not followed by a date, in a time converted on a given day.
TIME_DIFFERENCE_EXPECTED_CITY	thrown	time difference between not followed by a city or a zone.
TIME_DIFFERENCE_EXPECTED_SECOND_CITY	thrown	time difference between <a> and not followed by a second city or zone.
OVERLAP_EXPECTED_HOURS	thrown	overlap of not followed by hours, as in 9am to 5pm.
OVERLAP_EXPECTED_IN	thrown	The hours of an overlap not followed by in and the places.
OVERLAP_EXPECTED_CITY	thrown	in not followed by a city or a zone, in an overlap.
TIMECODE_EXPECTED_FPS	thrown	A video timecode or frame count without its frame rate, as in at 30 fps.
TIMECODE_EXPECTED_FRAMES	thrown	A timecode followed by in and something other than frames.
TIMECODE_FRAME_OUT_OF_RANGE	thrown	A timecode whose frame number is not below the frame rate.
TIME_IN_ZONE_UNDATED	thrown	time in Tokyo on 1 March 2027: the time in a place is the time there now, not on another day. The message points at converting a time on that day instead.
ISO_DURATION_MALFORMED	either	An identifier shaped like an ISO 8601 duration that breaks its grammar, as P1H (a time part before the T) or P1D1D. The message says which rule it breaks.

TimezoneErrorCodes

In the package as ERROR_CODE_CATALOGUES.TimezoneErrorCodes.

Code	Arrives	When it arises
TIME_ZONE_SKIPPED_TIME	as a value	1:30am London on 29 March 2026 in Tokyo: the clocks went forward over 1:30, so it never happened in London that day.
TIME_ZONE_REPEATED_TIME	as a value	1:30am London on 25 October 2026 in Tokyo: the clocks went back over 1:30, so it happened twice and names no one moment.
TIME_ZONE_EXPECTED_DATE	as a value	3pm London on 5 in Tokyo, or 3pm on 5: the on clause was given something that is not a date.
TIME_ZONE_EXPECTED_TIME	as a value	t London in Tokyo where t holds something that is not a time (t = 5): a zone after a name converts the time of day it holds.
OVERLAP_NEEDS_TWO_ZONES	as a value	overlap of 9am to 5pm in London: one place has nothing to overlap with.
OVERLAP_HOURS_EMPTY	as a value	overlap of 9am to 9am in London and Paris: hours that start where they end have no length.

Travel

TravelErrorCodes

In the package as ERROR_CODE_CATALOGUES.TravelErrorCodes.

Code	Arrives	When it arises
TRIP_EXPECTED_DISTANCE	as a value	The first quantity was not a distance.
TRIP_EXPECTED_ECONOMY	as a value	The second quantity was not a fuel economy.
TRIP_EXPECTED_FUEL_PRICE	as a value	The price was not an amount of money for a volume.

Units

UomErrorCodes

In the package as ERROR_CODE_CATALOGUES.UomErrorCodes.

Code	Arrives	When it arises
COOKING_CONVERSION_REQUIRES_UNIT	as a value	A cooking conversion of a plain number, with no mass or volume unit.
COOKING_CONVERSION_UNSUPPORTED_UNIT	as a value	A cooking conversion from or to a unit that is not a mass or a volume.
COOKING_UNKNOWN_INGREDIENT	as a value	A cooking conversion between mass and volume for an ingredient with no density in the table.

Variables

VariablesErrorCodes

In the package as ERROR_CODE_CATALOGUES.VariablesErrorCodes.

Code	Arrives	When it arises
EXPECTED_IDENTIFIER	thrown	A : or global : not followed by a name, as in := 5.
NAME_HAS_RESERVED_WORD	thrown	A name of several words holding a word the engine already reads: an operator spelled as a word, first or last (take home = 5, monthly take = 4000), or a phrase (tax on = 5). The message names the word.
NAME_HAS_QUOTE_MARK	thrown	A name of several words with a quote mark that is not an apostrophe in a word (Alice‘s food = 3), or an apostrophe before a word’s first letter (’tis rate = 5). The message names the mark.

Weather

WeatherErrorCodes

In the package as ERROR_CODE_CATALOGUES.WeatherErrorCodes.

Code	Arrives	When it arises
WEATHER_GEOCODING_API_ERROR	thrown	Open-Meteo’s geocoding endpoint returned a non-OK HTTP status.
WEATHER_CITY_NOT_FOUND	thrown	Geocoding succeeded (200 OK) but matched no place for the given name, most likely a typo in the city, not an API failure.
WEATHER_FORECAST_API_ERROR	thrown	Open-Meteo’s forecast endpoint returned a non-OK HTTP status.
WEATHER_FORECAST_RESPONSE_MALFORMED	thrown	Forecast endpoint returned 200 OK but the response body is missing the expected current/daily blocks, an API contract violation, not a local bug.
WEATHER_UNKNOWN_QUERY_KIND	thrown	WeatherPackage.ts’s fetchQuery switch fell through to its default case, unreachable via this package’s own parselets, an internal invariant violation if it ever happens.
WEATHER_EXPECTED_CITY	thrown	A weather form (weather in, temperature in) not followed by a city.

What-if and sweeps

WhatIfErrorCodes

In the package as ERROR_CODE_CATALOGUES.WhatIfErrorCodes.

Code	Arrives	When it arises
WHAT_IF_NO_DOCUMENT	as a value	A what-if or a sweep evaluated with no document to re-run.
WHAT_IF_TARGETS_ITSELF	as a value	A what-if or a sweep naming its own line, which it would re-run.
WHAT_IF_REQUIRES_VARIABLE_NAME	thrown	A what-if with no name to change after with.
WHAT_IF_DUPLICATE_INPUT	thrown	A what-if that sets the same name twice.
WHAT_IF_TOO_MANY_INPUTS	thrown	A what-if changing more inputs than one takes.
WHAT_IF_INPUT_PENDING	as a value	A what-if whose input is still waiting on live data.
SWEEP_REQUIRES_VARIABLE_NAME	thrown	A sweep with no name to step through after for.
SWEEP_REQUIRES_STEP	thrown	A sweep with no step after its range.
SWEEP_RANGE_NOT_NUMERIC	as a value	A sweep whose start, end or step is not a finite number, percentage or quantity.
SWEEP_RANGE_MISMATCH	as a value	A sweep whose start, end and step are not all the same kind of value.
SWEEP_STEP_ZERO	as a value	A sweep with a step of zero, which never reaches its end.
SWEEP_STEP_WRONG_SIGN	as a value	A sweep whose step moves away from its end.
SWEEP_TOO_MANY_STEPS	as a value	A sweep that would try more values than one sweep allows.
SWEEP_TOO_MUCH_WORK	as a value	A sweep that would re-run more lines in all than one sweep allows.
SWEEP_OVER_BUDGET	as a value	A sweep whose steps together reached a limit on the work one evaluation may do.
SWEEP_STEP_FAILED	as a value	A sweep one of whose steps failed. The message names the input value and the failure.
SWEEP_ANSWER_NOT_NUMERIC	as a value	A sweep one of whose answers is not a number or a quantity, which is all a sweep lists.
SWEEP_ANSWER_PERCENTAGE	as a value	A sweep of a line that answers a percentage, which a list (a row of plain numbers) cannot hold.
SWEEP_DATE_STEP_NOT_DURATION	as a value	A sweep between two dates whose step is not a length of time (step 5), or is working days.
SCENARIO_UNKNOWN	as a value	line N under bull with no scenario bull with ... line above it.
SCENARIO_DUPLICATE	as a value	line N under bull where two lines above both declare a scenario named bull.