Rules / Output

Package hyperref Warning: Token not allowed in a PDF string (Unicode) — Heading simplified in PDF bookmarks

hyperref removed math or commands from a heading when making the PDF bookmark.

Fix

Use \texorpdfstring{TeX}{plain text} in the heading.

Example

Reproduced on TeX Live 2026 by CI · pdflatex · corpus/math-in-pdf-bookmark

Math in a section title with hyperref

Fails: main.tex
\documentclass{article}
\usepackage{hyperref}
\begin{document}
\section{Convergence for $\alpha < 1$}
Text.
\end{document}
Fixed
\documentclass{article}
\usepackage{hyperref}
\begin{document}
\section{Convergence for \texorpdfstring{$\alpha < 1$}{alpha < 1}}
Text.
\end{document}
What TeX prints in main.log
Package hyperref Warning: Token not allowed in a PDF string (Unicode):
(hyperref)                removing `math shift' on input line 4.
Package hyperref Warning: Token not allowed in a PDF string (Unicode):
(hyperref)                removing `\alpha' on input line 4.
Package hyperref Warning: Token not allowed in a PDF string (Unicode):
(hyperref)                removing `math shift' on input line 4.