Appendix F Standard Errors

Here is a list of the more important error symbols in standard Emacs, grouped by concept. The list includes each symbol's message and a cross reference to a description of how the error can occur.

Each error symbol has a set of parent error conditions that is a list of symbols. Normally this list includes the error symbol itself and the symbol error. Occasionally it includes additional symbols, which are intermediate classifications, narrower than error but broader than a single error symbol. For example, all the errors in accessing files have the condition file-error. If we do not say here that a certain error symbol has additional error conditions, that means it has none.

As a special exception, the error symbol quit does not have the condition error, because quitting is not considered an error.

Most of these error symbols are defined in C (mainly data.c), but some are defined in Lisp. For example, the file userlock.el defines the file-locked and file-supersession errors. Several of the specialized Lisp libraries distributed with Emacs define their own error symbols. We do not attempt to list of all those here.

See Errors, for an explanation of how errors are generated and handled.

error

The message is ‘error’. See Errors.

quit

The message is ‘Quit’. See Quitting.

args-out-of-range

The message is ‘Args out of range’. This happens when trying to access an element beyond the range of a sequence, buffer, or other container-like object. See Sequences Arrays Vectors, and See Text.

arith-error

The message is ‘Arithmetic error’. This occurs when trying to perform integer division by zero. See Numeric Conversions, and See Arithmetic Operations.

beginning-of-buffer

The message is ‘Beginning of buffer’. See Character Motion.

buffer-read-only

The message is ‘Buffer is read-only’. See Read Only Buffers.

circular-list

The message is ‘List contains a loop’. This happens when a circular structure is encountered. See Circular Objects.

cl-assertion-failed

The message is ‘Assertion failed’. This happens when the cl-assert macro fails a test. See Assertions.

coding-system-error

The message is ‘Invalid coding system’. See Lisp and Coding Systems.

cyclic-function-indirection

The message is ‘Symbol's chain of function indirections contains a loop’. See Function Indirection.

cyclic-variable-indirection

The message is ‘Symbol's chain of variable indirections contains a loop’. See Variable Aliases.

dbus-error

The message is ‘D-Bus error’. This is only defined if Emacs was compiled with D-Bus support. See Errors and Events.

end-of-buffer

The message is ‘End of buffer’. See Character Motion.

end-of-file

The message is ‘End of file during parsing’. Note that this is not a subcategory of file-error, because it pertains to the Lisp reader, not to file I/O. See Input Functions.

file-already-exists

This is a subcategory of file-error. See Writing to Files.

file-date-error

This is a subcategory of file-error. It occurs when copy-file tries and fails to set the last-modification time of the output file. See Changing Files.

file-error

We do not list the error-strings of this error and its subcategories, because the error message is normally constructed from the data items alone when the error condition file-error is present. Thus, the error-strings are not very relevant. However, these error symbols do have error-message properties, and if no data is provided, the error-message property is used. See Files.

file-missing

This is a subcategory of file-error. It occurs when an operation attempts to act on a file that is missing. See Changing Files.

compression-error

This is a subcategory of file-error, which results from problems handling a compressed file. See How Programs Do Loading.

file-locked

This is a subcategory of file-error. See File Locks.

file-supersession

This is a subcategory of file-error. See Modification Time.

file-notify-error

This is a subcategory of file-error. It happens, when a file could not be watched for changes. See File Notifications.

ftp-error

This is a subcategory of file-error, which results from problems in accessing a remote file using ftp. See Remote Files.

invalid-function

The message is ‘Invalid function’. See Function Indirection.

invalid-read-syntax

The message is ‘Invalid read syntax’. See Printed Representation.

invalid-regexp

The message is ‘Invalid regexp’. See Regular Expressions.

mark-inactive

The message is ‘The mark is not active now’. See The Mark.

no-catch

The message is ‘No catch for tag’. See Catch and Throw.

scan-error

The message is ‘Scan error’. This happens when certain syntax-parsing functions find invalid syntax or mismatched parentheses. Conventionally raised with three argument: a human-readable error message, the start of the obstacle that cannot be moved over, and the end of the obstacle. See List Motion, and See Parsing Expressions.

search-failed

The message is ‘Search failed’. See Searching and Matching.

setting-constant

The message is ‘Attempt to set a constant symbol’. This happens when attempting to assign values to nil, t, most-positive-fixnum, most-negative-fixnum, and keyword symbols. It also happens when attempting to assign values to enable-multibyte-characters and some other symbols whose direct assignment is not allowed for some reason. See Constant Variables.

text-read-only

The message is ‘Text is read-only’. This is a subcategory of buffer-read-only. See Special Properties.

undefined-color

The message is ‘Undefined color’. See Color Names.

user-error

The message is the empty string. See Signaling Errors.

user-search-failed

This is like ‘search-failed’, but doesn't trigger the debugger, like ‘user-error’. See Signaling Errors, and See Searching and Matching. This is used for searching in Info files, See Search Text.

void-function

The message is ‘Symbol's function definition is void’. See Function Cells.

void-variable

The message is ‘Symbol's value as variable is void’. See Accessing Variables.

wrong-number-of-arguments

The message is ‘Wrong number of arguments’. See Argument List.

wrong-type-argument

The message is ‘Wrong type argument’. See Type Predicates.