LaTeX Compilation Failed? Locate and Fix the Error in Three Steps
Check the current compilation status, then inspect the first real error. Later messages may be consequences of the same original problem rather than separate issues.
Step 1: Check the Job and First Error
Wait for queued or running jobs to finish. Open the toolbar's Bug panel and inspect the errors and Original Log. Two common formats are:
! Undefined control sequence.
l.42 \texbf{Results}
./main.tex:42: Undefined control sequence.
Here, \texbf is a typo for \textbf. Bibliography-processing failures and timeouts may use different messages; inspect the actual job failure.
Step 2: Locate the File, Line, and Context
l.42 or main.tex:42 identifies where TeX detected a problem, not necessarily where it began. A missing brace can surface in the next paragraph. Identify the main file, chapter, or template involved, then inspect earlier grouping and environment boundaries.
For entries with a valid file and line, use Locate to position. Fix the first error, compile again, and reassess any independent problems.
Step 3: Isolate Complete Blocks in a Copy
Download the source project or keep a recoverable version before broad changes:
- Inspect the most recent edit first.
- Divide by complete sections, equations, tables, or lists; do not cut command arguments.
- Temporarily remove roughly half the suspect material while preserving the preamble and dependencies.
- Narrow the region according to whether the original error remains. Restore missing dependencies if the test creates new undefined commands.
A Visible PDF Does Not Establish Success
- Warnings may accompany a generated PDF; inspect layout and overflow.
- The preview can show an older result if the latest source did not compile successfully. Check the main file and current job.
- Preview with errors — not verified means further investigation is needed.
Compare with a Minimal Project
Create a blank test project, choose pdfLaTeX, and put this complete example in its main file. Add the original content and dependencies incrementally:
\documentclass[a4paper,11pt]{article}
\usepackage{amsmath}
\begin{document}
This is a minimal test document.
\end{document}
Three Common Errors
| Message | Possible cause | Action |
|---|---|---|
Undefined control sequence | Typo or missing definition | Check spelling, project macros, and packages |
Missing $ inserted | Mathematical content in text mode | Use a math environment such as \(...\) |
Extra }, or forgotten $ | Broken grouping or math delimiters | Inspect earlier braces and math boundaries |
Ask Agent to Investigate
AI Fix in the Bug panel opens Agent and submits a debugging request. You can also ask through Chat & Agent: “Locate the first real compilation error, make only necessary changes, compile, and report remaining issues.” Review the changes and the current job, then inspect the PDF.
See bibliography management for reference issues and preventing AI-generated errors for generation problems.