"! Undefined control sequence. <argument> \fail" after update. But what package?

[Zdenek Wagner]

Hi,

as default, LaTeX does not trace the error, it just displays the line
number but not the file and does not show what triggered the error.
Add the following to the beginning of your main file:

\errorcontextlines=999

It will then show the complete trace of the expansion leading to the
undefined control sequence.

Zdeněk Wagner
http://ttsm.icpf.cas.cz/team/wagner.shtml

čt 6. 1. 2022 v 14:44 odesílatel Markus Kohm <komascript at gmx.info> napsal:
>
> Am Donnerstag, 6. Januar 2022, 14:27:05 CET schrieb Alexander Krumeich:
> > I'm sorry I can't provide an MWE here.
>
> Providing a MWE is always possible. It's just a matter of effort. And without
> any code shown, every answer would be speculation. Nevertheless I would
> speculate that the lines 112 and 116 of one of your TeX files use xpatch to
> patch some code of either LaTeX or a class or package and the patch fails
> after the update, because the relevant code has changed in LaTeX or the class
> or the package.
>