Common LaTeX Errors (from Someone Who’s Broken LaTeX Too Many Times)

I’ve broken LaTeX compilation more times than I can count.

Missing dollar signs. Extra braces. Images that definitely exist but LaTeX insists don’t. More than once, I’ve stared at an error message five minutes before a deadline, convinced LaTeX was trolling me.

The funny part? Most LaTeX errors look scary but are caused by something very small—usually a typo a few lines above where LaTeX is yelling at you.

Last semester alone: I broke compilation on my Gold Price Prediction report three times (same error each time—I never learn). My Blockchain Document Verification documentation refused to compile because of one missing brace. And during finals week, I had a college report due in two hours that wouldn’t generate a PDF because of an image path issue.

Every. Single. Time. The fix was obvious in hindsight.

Below are the LaTeX errors I run into most often when writing assignments, reports, and long documents, along with how to actually fix them without losing your mind. These aren’t theoretical—these are errors I personally debugged at 2 AM with a deadline looming.

1. Missing $ or Misplaced Math Mode

Typical error:

! Missing $ inserted.

I once spent nearly two hours on this during my Gold Price Prediction report. We had statistical formulas throughout—mean squared error, accuracy metrics, all the math stuff. I wrote MSE = 0.15 in plain text thinking LaTeX would understand. It didn’t.

My project partner found the issue in 30 seconds: “Dude, you need dollar signs around math.”

Embarrassing? Yes. But now I never forget.

What causes it

You used math symbols (=, +, ^, subscripts, Greek letters) outside math mode.

LaTeX needs to know when you’re writing math. Plain text and math are rendered differently—different fonts, different spacing, different rules.

Examples

Wrong:

The accuracy improved from 0.70 to 0.85, a 15% increase.

Correct:

The accuracy improved from $0.70$ to $0.85$, a $15\%$ increase.

Wrong (inline math):

Our model achieved MSE = 0.15 on test data.

Correct (inline math):

Our model achieved $MSE = 0.15$ on test data.

For displayed equations (centered, on their own line):

\begin{equation}
E = mc^2
\end{equation}

% Or without numbering
\[ E = mc^2 \]

Real-world tip

Overleaf often points to the next line after the actual error. If line 47 shows the error, check line 45-46 first.

My debugging process:

1. Look at the line LaTeX mentions
2. Check 2-3 lines above it
3. Search for math symbols (=, %, Greek letters)
4. Add dollar signs: $...$

If you’re new to math syntax in LaTeX, the basic rule is: any mathematical expression needs $ around it for inline math, or \[...\] / equation environment for displayed math.

2. Undefined Control Sequence

Typical error:

! Undefined control sequence.
l.47 \mathbb
             {R}

This one hit me hard the first time I copied code from Stack Overflow at 1 AM while working on a machine learning assignment. I needed fancy math symbols for real numbers (ℝ), so I found \mathbb{R} online, pasted it, compiled… error.

Turns out you can’t just use any LaTeX command. Some require packages.

What causes it

1. Typo in a command – \tekst instead of \text
2. Missing package – Using \mathbb{} without loading amsmath
3. Wrong mode – Text command in math mode or vice versa
4. Obsolete command – Like \it (old) instead of \textit{} (modern)

Examples

Wrong (missing package):

\documentclass{article}
\begin{document}
The set of real numbers is denoted $\mathbb{R}$.
\end{document}

Correct:

\documentclass{article}
\usepackage{amsmath}  % Add this!
\begin{document}
The set of real numbers is denoted $\mathbb{R}$.
\end{document}

Common packages you’ll need:

\usepackage{amsmath}      % Advanced math
\usepackage{amssymb}      % Math symbols
\usepackage{graphicx}     % Images
\usepackage{hyperref}     % Clickable links
\usepackage{booktabs}     % Better tables
\usepackage{listings}     % Code blocks

My debugging checklist

When I see “Undefined control sequence”:

1. Check spelling – \tekst vs \text
2. Google the command – “latex mathbb” → see which package needed
3. Check preamble – Is \usepackage{amsmath} there?
4. Look for typos – \begin{centre} vs \begin{center} (I’ve done this)

Real mistake I made: In my college report template, I used \boldsymbol{} for bold Greek letters without loading amsmath. Took me 20 minutes to figure out because I was looking at the wrong part of the document.

Related: LaTeX Basic Commands and LaTeX Formatting Commands.

3. Extra } or Forgotten }

Typical error:

! Extra }, or forgotten \endgroup.

Or:

! Missing } inserted.

This error broke my major project report the night before submission. I was formatting my Gold Price Prediction results section, added emphasis to a bunch of text with \textbf{}, and somewhere in 20 pages, I missed one closing brace.

LaTeX pointed to line 347. The actual missing brace? Line 89.

The fix? One single } character.

What causes it

• Too many closing braces }
• Missing closing brace
• Mismatched \begin{} and \end{}

Examples

Wrong:

\textbf{Important finding about LSTM accuracy

The results show...

Correct:

\textbf{Important finding about LSTM accuracy}

The results show...

Wrong (nested braces):

\textbf{Bold text with \emph{emphasis}}

Correct:

\textbf{Bold text with \emph{emphasis}}

(This is actually correct—just make sure every { has a matching })

Survival tips

In Overleaf:

1. Click on a brace {
2. Overleaf highlights the matching }
3. If no highlight → missing brace

In TeXstudio:

• Shows brace matching with colors
• Hover over } to see corresponding {

My manual method (when desperate):

1. Copy problem section to new document
2. Delete half the content
3. Compile
4. If it works → problem is in deleted half
5. Restore and repeat (binary search debugging)

Real story: During finals, I had three reports due. One wouldn’t compile. At 3 AM, I couldn’t find the missing brace. I deleted sections until it compiled, found which section broke it, then carefully re-added content until I found the exact line. The missing brace was in a footnote I’d barely touched.

4. File Not Found (image.png not found)

Typical error:

! LaTeX Error: File `image.png` not found.

I’ve had LaTeX complain about an image that was literally right there in the project folder. I could see it. Overleaf could see it. LaTeX? “Nope, doesn’t exist.”

For my Blockchain project documentation, I had architecture diagrams. All PNG files. All in an images/ folder. Half of them worked. Half gave “file not found” errors.

Why? I named some files Diagram1.PNG (capital extension) and referenced them as diagram1.png (lowercase). Linux file systems are case-sensitive. Fixed all filenames to lowercase, problem solved.

What causes it

1. Wrong filename – image1.png vs Image1.png
2. Wrong path – images/plot.png vs plot.png
3. Wrong extension – File is JPG, you wrote PNG
4. File actually missing – You forgot to upload it to Overleaf

Examples

Wrong:

\includegraphics{images/results.png}
% But file is actually in root directory

Correct:

\includegraphics{results.png}
% Or specify the correct path
\includegraphics{./figures/results.png}

Pro tip – set graphics path:

\usepackage{graphicx}
\graphicspath{{./images/}{./figures/}}

% Now you can just write
\includegraphics{plot.png}
% LaTeX searches in images/ and figures/

My debugging process

When images won’t load:

1. Check exact filename – copy-paste from file manager
2. Check case sensitivity – Plot.PNG ≠ plot.png
3. Check file actually uploaded – in Overleaf, expand project files
4. Use relative paths – ./images/file.png more reliable than images/file.png
5. Let LaTeX find extension – write \includegraphics{plot} without .png, LaTeX finds it

Real mistake: My Gold Price Prediction report had graphs generated by Matplotlib. I saved them as prediction_plot.PNG(capital) but wrote \includegraphics{prediction_plot.png}. Worked on Windows (case-insensitive). Failed on Overleaf’s Linux servers. Always use lowercase extensions.

Related: LaTeX Figure Commands for more on handling images properly.

5. Misplaced Alignment Tab (&)

Typical error:

! Misplaced alignment tab character &.

This one usually appears when I forget that & only works inside certain environments.

I was creating a comparison table for my project report—comparing different ML models. Wrote something like:

Model & Accuracy & Training Time
Random Forest & 82% & 5 min

Outside any table environment. LaTeX: “What is this & doing here?”

What causes it

Using & outside tabular, align, array, or similar environments.

The & character is special in LaTeX—it means “next column” in tables or “alignment point” in equations. You can’t just use it in normal text.

Correct usage in tables

\begin{tabular}{|c|c|c|}
\hline
Model & Accuracy & Time \\
\hline
Random Forest & 82\% & 5 min \\
LSTM & 85\% & 20 min \\
\hline
\end{tabular}

Correct usage in equations

\begin{align}
E &= mc^2 \\
F &= ma
\end{align}

The & marks where equations should align (usually before =).

If you need literal & in text

Use \& for ampersand in text: Smith \& Johnson

My mistake: In my Flutter project documentation, I wrote “Dart & Flutter” without escaping. Should be Dart \& Flutter.

6. Overfull / Underfull \hbox

Typical warning:

Overfull \hbox (7.0pt too wide) in paragraph at lines 23--27

This warning shows up constantly in justified text, especially with long URLs or technical terms.

First time I saw it: “Is my document broken?”
Answer: No, it’s just LaTeX being picky about line breaks.

What causes it

LaTeX couldn’t break a line nicely. It tried to justify text but something was too long—usually:

• Long URLs
• Technical terms without good break points
• Long words in narrow columns
• Code snippets in text

Why it happens in my documents

Gold Price Prediction report:

We collected data from https://www.investing.com/commodities/gold-historical-data

That URL? Too long to fit on one line. LaTeX can’t break it nicely, so it overflows into the margin.

Better fixes (not just ignoring it)

For URLs:

\usepackage{hyperref}
\usepackage{url}

\url{https://www.investing.com/commodities/gold-historical-data}
% This allows line breaks at certain points

For long technical terms:

\usepackage{hyphenat}
% Or manually suggest break points
machine\-learning\-algorithm

General typography improvement:

\usepackage{microtype}
% This package makes small adjustments that often fix warnings

My approach:

1. First pass: Add \usepackage{microtype} – fixes ~50% of warnings
2. For URLs: Use \url{} command
3. For critical documents: Rewrite sentences to break naturally
4. For assignments: Sometimes I just ignore minor overfull warnings (under 5pt)

Don’t do this:

\sloppy  % Makes everything worse

\sloppy lets LaTeX put huge gaps between words. Your document looks bad. Only use for desperate debugging.

Can I ignore these warnings?

Small overflows (< 5pt): Usually invisible, safe to ignore
Large overflows (> 10pt): Text literally goes into margins, fix it
Many warnings: Your document probably looks bad, address them

7. Bibliography Not Appearing

Typical symptom: Citations show as [?] and bibliography section is empty.

This confused me for hours when writing my first technical report in LaTeX. I had references in a .bib file, used \cite{}commands, added \bibliography{references} at the end… but the bibliography was just blank.

What causes it

LaTeX needs multiple compilation passes for references:

1. First pass: LaTeX notes which citations you used
2. BibTeX/Biber pass: Generates bibliography from .bib file
3. Second pass: LaTeX includes bibliography
4. Third pass: All references resolved

If you only compile once, citations won’t work.

The fix

Compile sequence:

pdflatex document.tex
bibtex document        # or biber document
pdflatex document.tex
pdflatex document.tex

In Overleaf: Usually automatic, but sometimes you need to manually clear cache and recompile.

In TeXstudio: Use “Build & View” (F5) which runs the full sequence.

My setup

For my Gold Price Prediction report bibliography:

references.bib file:

@article{goldprediction2023,
    author = {Smith, John},
    title = {Time Series Forecasting for Commodity Prices},
    journal = {Journal of Finance},
    year = {2023}
}

In main document:

\usepackage[backend=biber]{biblatex}
\addbibresource{references.bib}

\begin{document}
Our approach builds on previous work \cite{goldprediction2023}.

\printbibliography
\end{document}

Common mistakes I made:

1. File named wrong: reference.bib vs references.bib
2. Wrong path: .bib file in subfolder but didn’t specify path
3. Only compiled once: Need to compile multiple times
4. Used \bibliography{} with biblatex: Should use \printbibliography

8. Package Conflicts

Typical error:

! LaTeX Error: Command \textcurrency already defined.

This happened when I loaded too many packages without checking compatibility.

What causes it

Two packages define the same command, or packages loaded in wrong order.

Common conflicts:

• hyperref should be loaded last (almost always)
• inputenc with LuaLaTeX/XeLaTeX (not needed)
• Multiple font packages fighting

Example problem

\usepackage{times}
\usepackage{mathptmx}
% Both try to change fonts → conflict

My rule of thumb

Package loading order:

1. Font and encoding packages first
2. Math packages (amsmath, amssymb)
3. Graphics and figures (graphicx)
4. Tables and formatting
5. hyperref last

My standard preamble:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{booktabs}
\usepackage{hyperref}  % Always last

9. Special Characters Breaking Compilation

Typical error:

! Missing $ inserted.
! Undefined control sequence.

Special characters in LaTeX have specific meanings: %, $, &, #, _, ^, ~, \

Using them directly in text breaks things.

What I learned the hard way

In my project documentation:

% Wrong
Our model achieved 85% accuracy
Use C++ for performance
Cost: $500

Correct:

Our model achieved 85\% accuracy
Use C++ for performance  % Actually C++ works, but be careful
Cost: \$500

Escape sequences

• % → \%
• $ → \$
• & → \&
• # → \#
• _ → \_
• ^ → \^{}
• ~ → \~{}
• \ → \textbackslash{}

Common mistake: Writing file paths

% Wrong
C:\Users\Documents\project

% Correct
C:\textbackslash{}Users\textbackslash{}Documents\textbackslash{}project

% Better: use forward slashes
C:/Users/Documents/project

10. “Label(s) may have changed. Rerun”

Warning:

LaTeX Warning: Label(s) may have changed. Rerun to get cross-references right.

This one scared me when I was new. “Changed labels? What does that mean? Did I break something?”

What causes it

References (\label{} and \ref{}) need multiple compilation passes to resolve correctly.

First compile: LaTeX notes labels exist
Second compile: LaTeX fills in correct numbers

The fix

Just compile again. That’s it.

Sometimes three times for complex documents with lots of cross-references.

Not actually an error

This is a warning, not an error. Your PDF still generates. But page numbers, figure numbers, or citations might be wrong (?? instead of actual numbers).

My workflow:

• Write content
• Compile once → see warnings
• Compile again → warnings gone
• Done

My LaTeX Debugging Process (What Actually Works)

After breaking LaTeX hundreds of times, here’s my systematic approach:

Step 1: Read the Error Message

Don’t panic. The error tells you:

• Line number (approximately)
• What LaTeX expected
• What went wrong

Example:

! Missing $ inserted.
<inserted text>
               $
l.47 Our MSE = 0.15
                    on test data

Translation: Line 47 has math (=) without dollar signs.

Step 2: Check 2-3 Lines Above

LaTeX often reports errors one line late. If line 47 is flagged, check lines 45-46.

Step 3: Look for Common Culprits

My checklist (in order):

1. Missing $ around math?
2. Missing } closing brace?
3. Image filename correct?
4. Package loaded in preamble?
5. Compiled multiple times for references?

Step 4: Binary Search for Complex Errors

If I can’t find the error:

1. Comment out half the document
2. Compile
3. If it works → error in commented half
4. If still broken → error in active half
5. Repeat until you find the problem section

Real example: My 25-page project report wouldn’t compile. I commented out pages 13-25. Still broken. Commented out pages 7-12. Worked! Error was in pages 7-12. Narrowed down to page 9. Found a stray $ in middle of paragraph.

Step 5: Use Overleaf’s Error Highlighting

Overleaf underlines problems in red/yellow. Click on the error for hints.

Step 6: Google the Exact Error

Copy the error message (first line), paste into Google with “latex”:

latex "Missing $ inserted"

99% chance someone on TeX Stack Exchange solved it.

Tools I Actually Use

Overleaf (online):

• Real-time error highlighting
• Logs show exactly what failed
• Easy to share for help

TeXstudio (local):

• Better for large projects
• Faster compilation
• Offline access
• Download TeXstudio

My preference: Overleaf for college assignments (collaborate with team), TeXstudio for personal projects (faster, more control).

When to Ask for Help

Sometimes you’re stuck. Genuinely stuck. Error makes no sense, Google finds nothing, you’ve been debugging for 2 hours.

Where I go for help:

1. TeX Stack Exchange – Best resource, search first then ask
2. Overleaf Documentation – Actually good, unlike most docs
3. LaTeX Project Official Docs – Comprehensive but dense
4. Classmates/Project Partner – Fresh eyes spot obvious mistakes

My project partner found the missing brace in my Gold Price Prediction report in 30 seconds after I’d been searching for an hour. Sometimes you just need someone else to look.

Final Thoughts: LaTeX Errors Aren’t That Scary

LaTeX errors feel cryptic when you’re new. But after breaking compilation enough times, you recognize patterns:

• 90% of errors are typos
• Missing $, }, or package explains most problems
• The reported line is usually 1-3 lines after the actual mistake
• Recompiling fixes half the warnings
• Most errors have simple fixes

My honest experience:

First semester: Every error was a crisis, took 30+ minutes to fix
Second semester: Most errors fixed in under 5 minutes
Now: I recognize error messages instantly and know the fix

The moment LaTeX “clicks” is when you stop fearing error messages and start reading them as clues.

If you’re building longer documents, templates help avoid errors from the start—see LaTeX Templates for Thesis, Articles, and Presentations.

Learning the basics prevents most errors—check out Writing Your First LaTeX Document and LaTeX Fundamentals.

For specific commands that commonly cause errors, see Basic LaTeX Commands.

LaTeX gets easier the moment you stop fighting it and start understanding what it’s trying to tell you. The error messages are actually helpful—once you learn to read them.

And when all else fails? Copy your document section by section into a new file until you find what breaks. It works every time.

Quick Reference: Error → Fix

Keep this handy. I still reference it when debugging at 2 AM.

For more LaTeX guides, Flutter tutorials, AI development, and web scraping, visit Deadloq.