# wrong type argument: number-or-marker-p, nil after upgrading auctex

After upgrading to auctex-13.0.1 I am getting the error wrong type argument: number-or-marker-p, nil whenever I try to compile a latex document in emacs.

Activating toggle-debug-on-error and issuing C-c c latex in a minimal latex document gives the following output:

Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
TeX-active-master-with-quotes(t t nil t)
apply(TeX-active-master-with-quotes (t t nil t))
TeX-command-expand("%%l%(mode)%' %T")
TeX-command("LaTeX" TeX-master-file nil)
TeX-command-master(nil)
funcall-interactively(TeX-command-master nil)
call-interactively(TeX-command-master nil nil)
command-execute(TeX-command-master)


Any ideas what's wrong here?

I'm quite sure it's not the file I'm using. Any minimal document throws the error. For example:

\documentclass{article}

\begin{document}
Hello.
\end{document}

• Please search this site for that error message. There are many occurrences, and most likely at least one is a duplicate of this question. – Drew Jan 1 at 19:44
• @Drew I've been searching this site, google, tex.stackexchange, and lots of other sites for hours. Yes, others have bumped into this error message. I haven't come across a post that's been helpful to me though. Maybe I missed something? Maybe you could point me in the direction of a post that would help? I'd happily see this marked as a duplicate if there's a legitimate duplicate. Otherwise, I'd like this question to stay posted because I'm hoping someone interested in helping me comes across it. – Brian Fitzpatrick Jan 1 at 20:22
• I cannot reproduce this (with auctex-13.0.1). Can you supply a minimal LaTeX file that demonstrates the behaviour? – Fran Burstall Jan 1 at 21:37
• @FranBurstall Thanks for looking at this. Every latex file throws the error. I'll add one, but I'm sure it's not the file causing the issue. – Brian Fitzpatrick Jan 1 at 21:54
• OK, looks like an issue with yr config (I still can't reproduce the error). Have a look at the Changes section of the auctex manual: looks like several variables like TeX-expand-list` have changed their behaviour in v13 and that might cause yr error. – Fran Burstall Jan 1 at 22:30