Papyrus Diagnose Compilation

Diagnose LaTeX Compilation

Turn a failed build into a located, classified, minimally-fixed error. Never mass-rewrite the source to "make it compile" — find the one thing that broke.

In Papyrus the app owns compilation (Cmd+S / Ctrl+S), so you normally read the error from the app's clickable diagnostics list rather than compiling yourself. The steps below apply whether you are reading that list or, outside the app, running the compiler directly.

Step 1 — Read the FIRST real error

Work from the first error, not the last: LaTeX errors cascade, and the tail of the log is usually damage from the head. In the app, the diagnostics list is already ordered — start at the top. If you do have a raw log, the first file:line: message (or ! …) line is the one to fix.

-file-line-error makes a compiler print file:line: message. If citations/refs are wrong (not the compile itself), the full cycle is pdflatex → bibtex/biber → pdflatex → pdflatex; Tectonic runs that cycle itself.

Step 2 — Classify and fix at the source line

Common cause → fix:

• Unescaped special char (_ % & # $ in text) → escape it (\_, \%, …).
• Unbalanced brace / missing } or \end{env} → match the environment.
• Undefined control sequence → missing \usepackage, or a typo'd/renamed macro.
• File 'x.sty' not found → package not installed in this TeX distribution; prefer a package the document already loads over telling the author to install one.
• File not found (graphic/\input) → wrong path or extension; confirm the file exists.
• Missing $ inserted → math symbol (_, ^, \alpha) used outside math mode; wrap in $…$ or an equation env.
• Missing \begin{document} → a stray character before the preamble ended.
• Bib: Citation 'key' undefined / stale .bbl → add the entry to the .bib (don't remove the \cite), then run bibtex/biber and two more pdflatex passes.
• There's no line here to end → a \\ on an otherwise-empty line.
• Overfull \hbox, Underfull, most Warning: lines are WARNINGS, not errors — do NOT "fix" them by hacking spacing (see papyrus-writing: never hack margins).

Apply the smallest fix at the identified line, recompile (ask the author to press Cmd+S, or rerun the compiler), and confirm THAT error is gone before moving on. Report what broke and exactly what you changed.