Why does LaTeX point to the wrong line number?

LaTeX often reports errors at the line where it notices the problem, not where the actual mistake is. A missing brace on line 50 might only cause an error on line 100 when LaTeX tries to close a group. Always check the lines before the reported location.

How do I fix errors that say Undefined control sequence?

This means you used a command that LaTeX does not recognize. Either you misspelled the command, forgot to load the required package, or the command does not exist. Check spelling first, then check if you need a usepackage statement.

What does Missing dollar sign inserted mean?

You used a mathematical symbol or operator outside of math mode. LaTeX inserts a dollar sign to try to help, but it usually makes things worse. Wrap your math in dollar signs for inline math or use an equation environment for displayed math.

Why do aux file errors keep appearing after I fix them?

LaTeX uses auxiliary files to track references and other data. Sometimes these files contain stale error information. Delete all .aux, .log, .toc, and .bbl files, then recompile from scratch.

What should I do when I get multiple errors at once?

Always fix the first error first. In LaTeX, one mistake often triggers a cascade of errors. Fix error number one, recompile, and many subsequent errors will disappear automatically.

How can I prevent LaTeX errors in the future?

Use a good editor with syntax highlighting, compile frequently to catch errors early, keep your preamble organized, and use version control so you can revert changes that break your document.

15 LaTeX Errors That Drive Researchers Crazy (And How to Fix Them in 30 Seconds)

When LaTeX Speaks in Ancient Curses

It's 11 PM. Your deadline is midnight. You hit compile and see:

! Missing $ inserted.
<inserted text>
                $
l.42 The value is α
                    = 0.05

Line 42 looks fine. The error message might as well be written in Sumerian. Your coffee is cold. Your patience is colder.

Here's the good news: there are only about 15 errors you'll ever see regularly. Once you learn to recognize them, debugging takes seconds instead of hours.

This guide decodes every common LaTeX error, explains what actually went wrong, and gives you copy-paste fixes.

Quick Debugging Strategy

Before diving into specific errors, here's the universal debugging approach that works 90% of the time:

Read the line number - Look at the l.XX in the error message
Check above that line - The actual error is often a few lines earlier
Look for unmatched braces - Missing } or { causes most errors
Delete auxiliary files - Sometimes .aux files cause phantom errors
Comment out sections - Binary search for the problematic code

Now let's tackle each error one by one.

1. Missing $ inserted

The Error:

! Missing $ inserted.
<inserted text>
                $
l.42 The value is α = 0.05

What Happened: You used a mathematical symbol (Greek letter, subscript, superscript, operator) outside of math mode. LaTeX expects these symbols only inside $...$ or equation environments.

The Fix: Wrap mathematical content in math delimiters:

% Wrong - Greek letter outside math mode
The value is α = 0.05
 
% Right - Inline math mode
The value is $\alpha = 0.05$
 
% Also right - Display math
The value is:
\[\alpha = 0.05\]

Common Triggers:

Greek letters: α, β, γ → Use $\alpha$ , $\beta$ , $\gamma$
Subscripts: H₂O → Use $H_2O$
Superscripts: x² → Use $x^2$
Special operators: ± → Use $\pm$
Underscores in text: file_name → Use file\_name or \texttt{file_name}

2. Undefined control sequence

The Error:

! Undefined control sequence.
l.42 \begn{equation}

What Happened: LaTeX doesn't recognize the command you used. This is usually a typo or a missing package.

The Fix: Check the spelling of your command:

% Wrong - typo
\begn{equation}
\inclludegraphics{fig.png}
\textbf{bold}
 
% Right - correct spelling
\begin{equation}
\includegraphics{fig.png}
\textbf{bold}

If the spelling is correct, you probably need to load a package:

% Commands and their required packages
\usepackage{graphicx}   % for \includegraphics
\usepackage{amsmath}    % for \align, \text, \boldsymbol
\usepackage{hyperref}   % for \href, \url
\usepackage{xcolor}     % for \textcolor
\usepackage{booktabs}   % for \toprule, \midrule, \bottomrule

Debugging Tip: The error message shows exactly which command failed. Look at what comes after the line number—that's your undefined command.

3. Missing begin document

The Error:

! LaTeX Error: Missing \begin{document}.
l.1 T
     his is my text

What Happened: You have text before \begin{document}, or you forgot to include it entirely. The preamble (everything before \begin{document}) can only contain commands, not actual content.

The Fix: Ensure your document structure is correct:

\documentclass{article}
\usepackage{amsmath}
% Preamble: only commands here, no text
 
\begin{document}
% Your content goes here
This is my text
\end{document}

Common Causes:

Stray characters at the start of the file (including invisible BOM characters)
Forgetting \begin{document} entirely
Putting text in the preamble by accident

4. Environment undefined / Undefined environment

The Error:

! LaTeX Error: Environment align undefined.

What Happened: You tried to use an environment that LaTeX doesn't know about. Either you misspelled it or forgot to load the package that defines it.

The Fix:

% align requires amsmath
\usepackage{amsmath}
\begin{align}
  x &= y + z \\
  a &= b + c
\end{align}
 
% lstlisting requires listings
\usepackage{listings}
\begin{lstlisting}
print("Hello")
\end{lstlisting}

5. File not found

The Error:

! LaTeX Error: File `myimage.png' not found.

What Happened: LaTeX can't locate the file you're trying to include. The file either doesn't exist, is in the wrong folder, or has a different name than specified.

The Fix:

% Check file location - use relative paths
\includegraphics{images/myimage.png}
 
% Or use absolute path (not recommended)
\includegraphics{/Users/name/project/myimage.png}
 
% Set graphics path in preamble
\graphicspath{{images/}{figures/}}
\includegraphics{myimage.png}  % Will search in images/ and figures/

Checklist:

Is the file name spelled correctly (including extension)?
Is the file in the same directory as your .tex file?
Did you use the correct path separator (/ works on all systems)?
Is the file extension correct (.png, .jpg, .pdf)?

6. Too many }'s / Extra }

The Error:

! Too many }'s.
l.42 }

What Happened: You have more closing braces } than opening braces {. This often happens when you accidentally delete an opening brace or add an extra closing one.

The Fix: Count your braces! Most editors can highlight matching braces. Look for:

% Wrong - extra closing brace
\textbf{some text}}
 
% Right
\textbf{some text}
 
% Wrong - missing opening brace
\frac1}{2}
 
% Right
\frac{1}{2}

Prevention Tip: Use an editor that highlights matching braces and shows mismatches. VSCode, TeXShop, and Overleaf all do this.

7. Misplaced alignment tab character &

The Error:

! Misplaced alignment tab character &.
l.42 The R&D department

What Happened: The & character has special meaning in LaTeX (it's used for alignment in tables and equations). Using it in regular text causes this error.

The Fix: Escape the ampersand with a backslash:

% Wrong
The R&D department
 
% Right
The R\&D department
 
% In tables, & is correct for column separation
\begin{tabular}{ll}
  Name & Value \\
  Alpha & 0.05 \\
\end{tabular}

8. Mismatched begin and end environments

The Error:

! LaTeX Error: \begin{itemize} on input line 10 ended by \end{enumerate}.

What Happened: You started one environment but ended a different one. This is usually a copy-paste error or a typo.

The Fix: Make sure your begin and end environments match:

% Wrong - mismatched environments
\begin{itemize}
  \item First
  \item Second
\end{enumerate}
 
% Right - matching environments
\begin{itemize}
  \item First
  \item Second
\end{itemize}

Debugging Tip: The error message tells you both environments. Check the line number for \begin and find the corresponding \end.

9. Package clash / Option clash

The Error:

! LaTeX Error: Option clash for package xcolor.

What Happened: You loaded the same package twice with different options, or another package loaded it with incompatible options.

The Fix: Load the package once with all needed options, before other packages that might use it:

% Wrong - loading xcolor twice
\usepackage{xcolor}
\usepackage[dvipsnames]{xcolor}
 
% Right - load once with all options
\usepackage[dvipsnames,svgnames]{xcolor}
 
% Or load early with options before other packages
\PassOptionsToPackage{dvipsnames}{xcolor}
\usepackage{tcolorbox}  % This package loads xcolor internally

10. Float(s) lost

The Error:

! LaTeX Error: Float(s) lost.

What Happened: You have a float (figure or table) in a place where floats aren't allowed, like inside a minipage, parbox, or another float.

The Fix: Move the float outside the restricted environment:

% Wrong - float inside minipage
\begin{minipage}{0.5\textwidth}
  \begin{figure}
    \includegraphics{image.png}
  \end{figure}
\end{minipage}
 
% Right - use captionof instead
\usepackage{caption}
\begin{minipage}{0.5\textwidth}
  \centering
  \includegraphics{image.png}
  \captionof{figure}{My caption}
\end{minipage}

11. Overfull \hbox

The Warning:

Overfull \hbox (15.0pt too wide) in paragraph at lines 42--45

What Happened: This is a warning, not an error. LaTeX couldn't fit text within the margins, so it extends past the edge. This often happens with long words, URLs, or code.

The Fix: Several approaches:

% For URLs - use breakable URLs
\usepackage{url}
\url{https://very-long-url.com/path/to/resource}
 
% For long words - suggest hyphenation
super\-cali\-fragilistic
 
% For code - use breakable listings
\usepackage{listings}
\lstset{breaklines=true}
 
% Global fix - more permissive line breaking
\sloppy  % In preamble (use sparingly)

12. Runaway argument

The Error:

Runaway argument?
{This is some text that goes on and on...
! File ended while scanning use of \textbf.

What Happened: LaTeX started reading an argument (something in {...}) but never found the closing brace before the file ended or hit another problem.

The Fix: Find the missing closing brace:

% Wrong - missing closing brace
\textbf{This text is bold but I forgot to close it
 
More text here...
 
% Right
\textbf{This text is bold}
 
More text here...

Debugging Tip: The error shows what command was waiting for its closing brace. Search for that command and check its braces.

13. ! Emergency stop

The Error:

! Emergency stop.
<*> myfile.tex

What Happened: LaTeX encountered an error so severe it couldn't continue. This usually follows another error, or your file has fundamental structural problems.

The Fix: Look at the errors before this one—the emergency stop is a consequence, not the cause. Common causes:

Missing \end{document}
Severely corrupted file
Wrong file encoding
Multiple cascading errors

Start by fixing the first error, then recompile.

14. Dimension too large

The Error:

! Dimension too large.
l.42 \hspace{999999cm}

What Happened: You specified a dimension larger than LaTeX can handle (about 575cm or 16384pt).

The Fix: Use smaller dimensions or relative units:

% Wrong - too large
\hspace{1000cm}
 
% Right - reasonable size
\hspace{5cm}
 
% Better - relative units
\hspace{0.3\textwidth}
\vspace{2\baselineskip}

15. ! TeX capacity exceeded

The Error:

! TeX capacity exceeded, sorry [main memory size=5000000].

What Happened: Your document is too complex for TeX's memory limits. This can happen with huge documents, recursive macros, or complex TikZ graphics.

The Fix:

Externalize TikZ graphics: \usetikzlibrary{external} and \tikzexternalize
Split large documents using \include or \input
Simplify complex macros
Increase memory limits in your TeX distribution's configuration

Prevention: The 5-Minute Pre-Compile Checklist

Before compiling, quickly check:

Braces match - Every { has a }
Environments match - Every \begin{X} has \end{X}
Math mode is closed - Every $ has a closing $
Special characters escaped - &, %, _, #, $ need backslashes in text
Packages loaded - Required packages are in the preamble

When All Else Fails

If you're completely stuck:

Delete auxiliary files - Remove .aux, .log, .toc, .lof, .lot, .bbl, .blg
Binary search - Comment out half your document and compile. If it works, the error is in the other half. Repeat.
Start fresh - Copy your content into a minimal working document and add packages one by one
Check encoding - Ensure your file is UTF-8 encoded

Conclusion

LaTeX errors look intimidating, but they follow patterns. Once you've seen each error a few times, you'll fix them automatically.

Key takeaways:

Always fix the first error first
The line number is a hint, not the exact location
Most errors come from mismatched braces or missing packages
When stuck, delete auxiliary files and recompile

Now you're equipped to handle any LaTeX error. Save this guide for reference, and those 11 PM debugging sessions will be a thing of the past.

When LaTeX Speaks in Ancient Curses

It's 11 PM. Your deadline is midnight. You hit compile and see:

! Missing $ inserted.
<inserted text>
                $
l.42 The value is α
                    = 0.05

Line 42 looks fine. The error message might as well be written in Sumerian. Your coffee is cold. Your patience is colder.

Here's the good news: there are only about 15 errors you'll ever see regularly. Once you learn to recognize them, debugging takes seconds instead of hours.

This guide decodes every common LaTeX error, explains what actually went wrong, and gives you copy-paste fixes.

Quick Debugging Strategy

Before diving into specific errors, here's the universal debugging approach that works 90% of the time:

Read the line number - Look at the l.XX in the error message
Check above that line - The actual error is often a few lines earlier
Look for unmatched braces - Missing } or { causes most errors
Delete auxiliary files - Sometimes .aux files cause phantom errors
Comment out sections - Binary search for the problematic code

Now let's tackle each error one by one.

1. Missing $ inserted

The Error:

! Missing $ inserted.
<inserted text>
                $
l.42 The value is α = 0.05

What Happened: You used a mathematical symbol (Greek letter, subscript, superscript, operator) outside of math mode. LaTeX expects these symbols only inside $...$ or equation environments.

The Fix: Wrap mathematical content in math delimiters:

% Wrong - Greek letter outside math mode
The value is α = 0.05
 
% Right - Inline math mode
The value is $\alpha = 0.05$
 
% Also right - Display math
The value is:
\[\alpha = 0.05\]

Common Triggers:

Greek letters: α, β, γ → Use $\alpha$ , $\beta$ , $\gamma$
Subscripts: H₂O → Use $H_2O$
Superscripts: x² → Use $x^2$
Special operators: ± → Use $\pm$
Underscores in text: file_name → Use file\_name or \texttt{file_name}

2. Undefined control sequence

The Error:

! Undefined control sequence.
l.42 \begn{equation}

What Happened: LaTeX doesn't recognize the command you used. This is usually a typo or a missing package.

The Fix: Check the spelling of your command:

% Wrong - typo
\begn{equation}
\inclludegraphics{fig.png}
\textbf{bold}
 
% Right - correct spelling
\begin{equation}
\includegraphics{fig.png}
\textbf{bold}

If the spelling is correct, you probably need to load a package:

% Commands and their required packages
\usepackage{graphicx}   % for \includegraphics
\usepackage{amsmath}    % for \align, \text, \boldsymbol
\usepackage{hyperref}   % for \href, \url
\usepackage{xcolor}     % for \textcolor
\usepackage{booktabs}   % for \toprule, \midrule, \bottomrule

Debugging Tip: The error message shows exactly which command failed. Look at what comes after the line number—that's your undefined command.

3. Missing begin document

The Error:

! LaTeX Error: Missing \begin{document}.
l.1 T
     his is my text

What Happened: You have text before \begin{document}, or you forgot to include it entirely. The preamble (everything before \begin{document}) can only contain commands, not actual content.

The Fix: Ensure your document structure is correct:

\documentclass{article}
\usepackage{amsmath}
% Preamble: only commands here, no text
 
\begin{document}
% Your content goes here
This is my text
\end{document}

Common Causes:

Stray characters at the start of the file (including invisible BOM characters)
Forgetting \begin{document} entirely
Putting text in the preamble by accident

4. Environment undefined / Undefined environment

The Error:

! LaTeX Error: Environment align undefined.

What Happened: You tried to use an environment that LaTeX doesn't know about. Either you misspelled it or forgot to load the package that defines it.

The Fix:

% align requires amsmath
\usepackage{amsmath}
\begin{align}
  x &= y + z \\
  a &= b + c
\end{align}
 
% lstlisting requires listings
\usepackage{listings}
\begin{lstlisting}
print("Hello")
\end{lstlisting}

5. File not found

The Error:

! LaTeX Error: File `myimage.png' not found.

What Happened: LaTeX can't locate the file you're trying to include. The file either doesn't exist, is in the wrong folder, or has a different name than specified.

The Fix:

% Check file location - use relative paths
\includegraphics{images/myimage.png}
 
% Or use absolute path (not recommended)
\includegraphics{/Users/name/project/myimage.png}
 
% Set graphics path in preamble
\graphicspath{{images/}{figures/}}
\includegraphics{myimage.png}  % Will search in images/ and figures/

Checklist:

Is the file name spelled correctly (including extension)?
Is the file in the same directory as your .tex file?
Did you use the correct path separator (/ works on all systems)?
Is the file extension correct (.png, .jpg, .pdf)?

6. Too many }'s / Extra }

The Error:

! Too many }'s.
l.42 }

What Happened: You have more closing braces } than opening braces {. This often happens when you accidentally delete an opening brace or add an extra closing one.

The Fix: Count your braces! Most editors can highlight matching braces. Look for:

% Wrong - extra closing brace
\textbf{some text}}
 
% Right
\textbf{some text}
 
% Wrong - missing opening brace
\frac1}{2}
 
% Right
\frac{1}{2}

Prevention Tip: Use an editor that highlights matching braces and shows mismatches. VSCode, TeXShop, and Overleaf all do this.

7. Misplaced alignment tab character &

The Error:

! Misplaced alignment tab character &.
l.42 The R&D department

What Happened: The & character has special meaning in LaTeX (it's used for alignment in tables and equations). Using it in regular text causes this error.

The Fix: Escape the ampersand with a backslash:

% Wrong
The R&D department
 
% Right
The R\&D department
 
% In tables, & is correct for column separation
\begin{tabular}{ll}
  Name & Value \\
  Alpha & 0.05 \\
\end{tabular}

8. Mismatched begin and end environments

The Error:

! LaTeX Error: \begin{itemize} on input line 10 ended by \end{enumerate}.

What Happened: You started one environment but ended a different one. This is usually a copy-paste error or a typo.

The Fix: Make sure your begin and end environments match:

% Wrong - mismatched environments
\begin{itemize}
  \item First
  \item Second
\end{enumerate}
 
% Right - matching environments
\begin{itemize}
  \item First
  \item Second
\end{itemize}

Debugging Tip: The error message tells you both environments. Check the line number for \begin and find the corresponding \end.

9. Package clash / Option clash

The Error:

! LaTeX Error: Option clash for package xcolor.

What Happened: You loaded the same package twice with different options, or another package loaded it with incompatible options.

The Fix: Load the package once with all needed options, before other packages that might use it:

% Wrong - loading xcolor twice
\usepackage{xcolor}
\usepackage[dvipsnames]{xcolor}
 
% Right - load once with all options
\usepackage[dvipsnames,svgnames]{xcolor}
 
% Or load early with options before other packages
\PassOptionsToPackage{dvipsnames}{xcolor}
\usepackage{tcolorbox}  % This package loads xcolor internally

10. Float(s) lost

The Error:

! LaTeX Error: Float(s) lost.

What Happened: You have a float (figure or table) in a place where floats aren't allowed, like inside a minipage, parbox, or another float.

The Fix: Move the float outside the restricted environment:

% Wrong - float inside minipage
\begin{minipage}{0.5\textwidth}
  \begin{figure}
    \includegraphics{image.png}
  \end{figure}
\end{minipage}
 
% Right - use captionof instead
\usepackage{caption}
\begin{minipage}{0.5\textwidth}
  \centering
  \includegraphics{image.png}
  \captionof{figure}{My caption}
\end{minipage}

11. Overfull \hbox

The Warning:

Overfull \hbox (15.0pt too wide) in paragraph at lines 42--45

What Happened: This is a warning, not an error. LaTeX couldn't fit text within the margins, so it extends past the edge. This often happens with long words, URLs, or code.

The Fix: Several approaches:

% For URLs - use breakable URLs
\usepackage{url}
\url{https://very-long-url.com/path/to/resource}
 
% For long words - suggest hyphenation
super\-cali\-fragilistic
 
% For code - use breakable listings
\usepackage{listings}
\lstset{breaklines=true}
 
% Global fix - more permissive line breaking
\sloppy  % In preamble (use sparingly)

12. Runaway argument

The Error:

Runaway argument?
{This is some text that goes on and on...
! File ended while scanning use of \textbf.

What Happened: LaTeX started reading an argument (something in {...}) but never found the closing brace before the file ended or hit another problem.

The Fix: Find the missing closing brace:

% Wrong - missing closing brace
\textbf{This text is bold but I forgot to close it
 
More text here...
 
% Right
\textbf{This text is bold}
 
More text here...

Debugging Tip: The error shows what command was waiting for its closing brace. Search for that command and check its braces.

13. ! Emergency stop

The Error:

! Emergency stop.
<*> myfile.tex

What Happened: LaTeX encountered an error so severe it couldn't continue. This usually follows another error, or your file has fundamental structural problems.

The Fix: Look at the errors before this one—the emergency stop is a consequence, not the cause. Common causes:

Missing \end{document}
Severely corrupted file
Wrong file encoding
Multiple cascading errors

Start by fixing the first error, then recompile.

14. Dimension too large

The Error:

! Dimension too large.
l.42 \hspace{999999cm}

What Happened: You specified a dimension larger than LaTeX can handle (about 575cm or 16384pt).

The Fix: Use smaller dimensions or relative units:

% Wrong - too large
\hspace{1000cm}
 
% Right - reasonable size
\hspace{5cm}
 
% Better - relative units
\hspace{0.3\textwidth}
\vspace{2\baselineskip}

15. ! TeX capacity exceeded

The Error:

! TeX capacity exceeded, sorry [main memory size=5000000].

What Happened: Your document is too complex for TeX's memory limits. This can happen with huge documents, recursive macros, or complex TikZ graphics.

The Fix:

Externalize TikZ graphics: \usetikzlibrary{external} and \tikzexternalize
Split large documents using \include or \input
Simplify complex macros
Increase memory limits in your TeX distribution's configuration

Prevention: The 5-Minute Pre-Compile Checklist

Before compiling, quickly check:

Braces match - Every { has a }
Environments match - Every \begin{X} has \end{X}
Math mode is closed - Every $ has a closing $
Special characters escaped - &, %, _, #, $ need backslashes in text
Packages loaded - Required packages are in the preamble

When All Else Fails

If you're completely stuck:

Delete auxiliary files - Remove .aux, .log, .toc, .lof, .lot, .bbl, .blg
Binary search - Comment out half your document and compile. If it works, the error is in the other half. Repeat.
Start fresh - Copy your content into a minimal working document and add packages one by one
Check encoding - Ensure your file is UTF-8 encoded

Conclusion

LaTeX errors look intimidating, but they follow patterns. Once you've seen each error a few times, you'll fix them automatically.

Key takeaways:

Always fix the first error first
The line number is a hint, not the exact location
Most errors come from mismatched braces or missing packages
When stuck, delete auxiliary files and recompile

Now you're equipped to handle any LaTeX error. Save this guide for reference, and those 11 PM debugging sessions will be a thing of the past.

When LaTeX Speaks in Ancient Curses

Quick Debugging Strategy

1. Missing $ inserted

2. Undefined control sequence

3. Missing begin document

4. Environment undefined / Undefined environment

5. File not found

6. Too many }'s / Extra }

7. Misplaced alignment tab character &

8. Mismatched begin and end environments

9. Package clash / Option clash

10. Float(s) lost

11. Overfull \hbox

12. Runaway argument

13. ! Emergency stop

14. Dimension too large

15. ! TeX capacity exceeded

Prevention: The 5-Minute Pre-Compile Checklist

When All Else Fails

Conclusion

LaTeX Commands Cheatsheet

Frequently Asked Questions

When LaTeX Speaks in Ancient Curses

Quick Debugging Strategy

1. Missing $ inserted

2. Undefined control sequence

3. Missing begin document

4. Environment undefined / Undefined environment

5. File not found

6. Too many }'s / Extra }

7. Misplaced alignment tab character &

8. Mismatched begin and end environments

9. Package clash / Option clash

10. Float(s) lost

11. Overfull \hbox

12. Runaway argument

13. ! Emergency stop

14. Dimension too large

15. ! TeX capacity exceeded

Prevention: The 5-Minute Pre-Compile Checklist

When All Else Fails

Conclusion

LaTeX Commands Cheatsheet

Frequently Asked Questions