[pdftex] \pdfendlink ended up in different nesting level than \pdfstartlink

[Ulrike Fischer]

Am Mon, 24 Oct 2022 15:16:43 -0600 schrieb Karl Berry:

> Hi Aleks - thanks for the report.
> 
>     \pdfendlink ended up in different nesting level than \pdfstartlink
> 
> I get the same fatal error with your source file, on the second run, on
> page 276. (After making the many fonts needed.)
> 
> Unfortunately this is not something that can be fixed at the pdftex
> level. pdftex is just reporting what it's seeing in terms of low-level
> PDF output. It is the LaTeX macros that need to avoid the issue. And as
> I recall, that is not even possible in all cases.

Well the actual error is not directly about \pdfendlink, that is
only a warning before the error:

pdfTeX warning: \pdfendlink ended up in different nesting level than
\pdfstartlink
! This can't happen (pdfvlistout).
<argument> ...shipout:D \box_use:N \l_shipout_box 

\__shipout_drop_firstpage_...
l.22 \ShowEq{Left and Right Eigenvalues 1}{cr}
                                              
I'm broken. Please show this to someone who can fix can fix


Beside this we have removed the box which triggered the
warning/error some years ago, so here is something new.
 
> You can report it at https://github.com/latex3/latex2e/issues, but your
> document is very complicated. They may not be able to debug the
> problem.

My incentive to debug a document with nearly 300 pages, lots of home
made commands and using an inputencoding different to utf8 is quite
low but I did take a look. 

Getting the nesting warning is quite easy: the document uses paracol
and you only need a link going over a page to trigger it.

But the actual error is difficult. The following gives it for me

\documentclass{article}
\usepackage[T2A]{fontenc}
\usepackage{paracol}
\usepackage[colorlinks]{hyperref}
\usepackage{lipsum}
\textheight=8\baselineskip
\begin{document}\showoutput 
\begin{paracol}{2}
\vspace*{7\baselineskip}
aa\\
\href{blub}{\lipsum[1]Привет Привет Привевевеве}
\switchcolumn
\vspace*{7\baselineskip}
aa\\
bbb\href{blub}{\lipsum[1-2] Привет Привет Привевевеве}
\end{paracol}
\end{document}

Small changes, e.g. removing colorlinks can avoid it, in other cases
one doesn't get an error but pdflatex simply crashes.
 


-- 
Ulrike Fischer 
http://www.troubleshooting-tex.de/