Guide to LaTeX (4th Edition) (Tools and Techniques

C
Error Messages
Errors are bound to be made at times during the preparation of a long
L AT E X document. The mistakes can be of various kinds, from simple typing
errors for command names to forgetting that some commands must be
paired or giving an incorrect syntax for a complicated command.
Errors during the L AT E X processing produce a list of messages on the
monitor, which appear totally incomprehensible to the beginner. Even the
advanced user can have difficulty figuring out a particular error message.
However, these messages contain information about fundamental structures
that can aid an experienced T E X programmer to see much deeper
into the heart of the problem.
In addition, the error messages contain useful information even for
the beginner. It is the purpose of this chapter to explain some of these
messages that can be of assistance to non-programmers.
Error messages are written both to the computer monitor and to the
processing transcript file, with extension .log. Examine this file if the
messages on the monitor went by too fast.
C.1 Basic structure of error messages
Error messages have two sources: those from L AT E X and those from the
underlying T E X program. The L AT E X messages are often followed by T E X
messages since L AT E X operates at a higher level.
C.1.1 T E X error messages
We start with a simple error as an example.
\documentclass{article}
\begin{document}
The last words appear in \txetbf{bold face}.
\end{document}
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