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Don’t panic! LaTeX errors can look scary, but most are easy to fix once you understand them. This guide covers the most common errors with clear solutions.
Quick tip: LaTeX error messages show the line number where the error occurred. Look for l.123 in the error message to find line 123 in your document.

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Understanding LaTeX Error Messages

LaTeX errors follow this pattern: 
! LaTeX Error: [Error description]

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.123 \textbf{This is the problematic line
Key parts:
  • ! indicates an error (not a warning)
  • Error description tells you what went wrong
  • l.123 shows the line number
  • The line content helps locate the issue

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Most Common Errors

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1. Missing $ inserted

Error message: 
! Missing $ inserted.
<inserted text> 
                $
l.42 The value of x_1 is important
Cause: Math symbols used outside math mode Solutions: 
The value of x_1 is important       % Wrong
The equation x^2 + y^2 = r^2 holds  % Wrong
Common math symbols that need math mode: _, ^, \alpha, \sum, etc.

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2. Undefined control sequence

Error message: 
! Undefined control sequence.
l.15 \textcolor
      {red}{This text}
Cause: Using a command that doesn’t exist or missing package Solutions: 
% Add required package
\usepackage{xcolor}  % For \textcolor
\usepackage{amsmath} % For \text
\usepackage{graphicx} % For \includegraphics

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3. Missing \begin

Error message: 
! LaTeX Error: Missing \begin{document}.
Cause: Content before \begin{document} or missing the command entirely Solution: 
\documentclass{article}
\title{My Document}

This is my text  % Wrong - content before \begin{document}

\begin{document}
\end{document}

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4. File not found

Error message: 
! LaTeX Error: File `mycustom.sty' not found.
Cause: Missing package, image, or bibliography file Solutions:
  1. Install missing package: 
    tlmgr install packagename  # TeX Live
# or use your TeX distribution's package manager
  2. Check file paths: 
    \includegraphics{images/photo.png}  % Make sure path is correct
\bibliography{references}           % Check references.bib exists
  3. Use correct file extensions: 
    \usepackage{mycustom}     % Looks for mycustom.sty
\input{chapter1}          % Looks for chapter1.tex

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5. Missing } inserted

Error message: 
! Missing } inserted.
<inserted text> 
                }
l.33 \textbf{Bold text
Cause: Unmatched braces Solution: 
\textbf{Bold text         % Missing closing brace
\textit{Italic {nested}   % Missing closing brace
$x^{2+3$                  % Missing closing brace
Use a text editor with brace matching to catch these errors early.

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6. Environment undefined

Error message: 
! LaTeX Error: Environment equation* undefined.
Cause: Using an environment that doesn’t exist or missing package Solution: 
% For equation* environment
\usepackage{amsmath}

% Check spelling
\begin{ennumerate}  % Wrong
\begin{enumerate}   % Correct

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7. Runaway argument

Error message: 
Runaway argument?
{This is a very long...
! Paragraph ended before \textbf was complete.
Cause: Missing closing brace or bracket spanning paragraphs Solution: 
\textbf{This is bold

This is a new paragraph}  % Error - can't span paragraphs

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8. Overfull/Underfull hbox

Warning message: 
Overfull \hbox (15.0pt too wide) in paragraph at lines 42--45
Cause: Text doesn’t fit properly in the line Solutions:
  1. Let LaTeX hyphenate: 
    \usepackage[english]{babel}
  2. Force hyphenation: 
    super\-cali\-fragi\-listic
  3. Rewrite the sentence
  4. Allow stretchy spacing: 
    \sloppy  % For whole document
{\sloppy This problematic paragraph}  % For specific text

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9. Table/Figure positioning problems

Issue: Tables or figures appear in wrong locations Solutions: 
% Use positioning options
\begin{figure}[htbp]  % here, top, bottom, page
\centering
\includegraphics{image}
\caption{My figure}
\end{figure}

% Force position (not recommended)
\usepackage{float}
\begin{figure}[H]  % Exactly Here

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10. Bibliography not showing

Issue: References not appearing Solution sequence: 
pdflatex document.tex
bibtex document       # or biber document
pdflatex document.tex
pdflatex document.tex

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Error Categories

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Math Mode Errors

Common math mode mistakes:
  • Text in math: Use \text{...} from amsmath
  • Wrong delimiter size: Use \left( and \right)
  • Display math in wrong place: Can’t use $$ in some environments
% Text in math mode
$x = 2 when y = 3$        % Wrong
$x = 2 \text{ when } y = 3$  % Correct

% Delimiter sizing
$(\frac{a}{b})$           % Small parentheses
$\left(\frac{a}{b}\right)$    % Auto-sized parentheses

% Display math
\begin{center}
$$x = y$$                 % Wrong in center environment
\end{center}

\begin{center}
$x = y$                   % Correct
\end{center}

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Package Conflicts

Some packages don’t work well together: 
% Common conflicts
\usepackage{subfigure}  % Old, conflicts with many
\usepackage{subfig}     % Use this instead

\usepackage{pdfpages}   % Load after graphicx
\usepackage{hyperref}   % Usually load last

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Font Errors

% Font not found
\usepackage{times}      % Deprecated
\usepackage{mathptmx}   % Use this instead

% Font size errors
\fontsize{50}           % Wrong - missing unit
\fontsize{50pt}{60pt}\selectfont  % Correct

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Debugging Strategies

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1. Binary Search Method

Comment out half your document to isolate errors: 
\begin{document}
First part...
%{
Second part...  % This part is now commented
%}
\end{document}

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2. Minimal Working Example (MWE)

Create a minimal file that reproduces the error: 
\documentclass{article}
\usepackage{[only needed packages]}
\begin{document}
[Minimal code that causes error]
\end{document}

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3. Check the Log File

Look for:
  • First error (fix this first)
  • Line numbers
  • Package warnings
  • Overfull/underfull boxes

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4. Common Quick Fixes

Clear auxiliary files

Delete .aux, .log, .toc files and recompile

Update packages

Keep your TeX distribution updated

Check encoding

Save files as UTF-8

Simplify first

Remove packages/commands until it works

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Prevention Tips

Best practices to avoid errors:
  1. Compile frequently (after every few lines when learning)
  2. Use a good editor with syntax highlighting
  3. Keep backups before major changes
  4. Organize long documents into multiple files
  5. Comment your code for complex parts
  6. Use version control (Git)

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Platform-Specific Issues

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Windows

  • Path issues: Use forward slashes / or double backslashes \\
  • Font issues: Install fonts system-wide
  • Encoding: Save as UTF-8, not ANSI

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macOS

  • Missing fonts: Install MacTeX fully
  • Path issues: Don’t use spaces in filenames
  • Preview issues: Use external PDF viewer

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Linux

  • Permission issues: Check file permissions
  • Missing packages: Use distribution package manager
  • Font issues: Update font cache

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Getting Help

When asking for help online, include:
  1. Minimal Working Example (MWE)
  2. Complete error message
  3. TeX distribution and version
  4. What you’ve already tried

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Help Resources

TeX StackExchange

Q&A community for TeX/LaTeX

LaTeX Community

Official LaTeX forum

Reddit r/LaTeX

Reddit community

CTAN

Package documentation

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Quick Reference Card

ErrorQuick Fix
Missing $Wrap math in $...$
Undefined control sequenceCheck spelling or add package
Missing }Match all opening braces
File not foundCheck path and filename
Overfull hboxAdd hyphenation or rewrite
Figure in wrong placeUse [htbp] positioning
Bibliography missingRun BibTeX/Biber
Package unknownInstall with package manager
Remember: Every LaTeX user encounters errors. They’re not a sign of failure but an opportunity to learn. The more errors you fix, the better you become at LaTeX!
Still stuck? Create a Minimal Working Example and ask for help in the community forums. Happy TeXing!