link error if links are in different levels.

[u-fischer]

This compiles fine but breaks if tagpdf is loaded.

\RequirePackage{pdfmanagement}
%\RequirePackage{tagpdf}
\documentclass{article}
\usepackage{hyperref}
\textheight=50mm
\title{}
\author{}
\begin{document}
\hsize=40mm
\parindent=0pt
\null\vskip30mm
\showoutput

Some multiline text with a rather long, breaking url \url{https://tex.stackexchange.com/questions/731156/the-bottom-margin-of-bibliography-frame-is-too-narrow}.
\enlargethispage{1sp}

\clearpage

\end{document}

@zauguin if you have an idea ...

[zauguin]

Which engine? For pdflatex I get the mismatched level warning for both versions, for LuaLaTeX I get

! Undefined control sequence.
\sys_if_output_pdf_p:

[u-fischer]

@zauguin it is about luatex, and actually I was writing a bit of nonsense, it errors in both cases but the error is different depending on if tagpdf is loaded or not.

I just sent a new pdfmanagement to ctan which will fix the unrelated sys_if_output error. Until then you need to load the backend first to test:

\ExplSyntaxOn\sys_ensure_backend:\ExplSyntaxOff
\RequirePackage{pdfmanagement}
\RequirePackage{tagpdf}
\documentclass{article}
\usepackage{hyperref}
\textheight=50mm
\title{}
\author{}
\begin{document}
\hsize=40mm
\parindent=0pt
\null\vskip30mm
\showoutput

Some multiline text with a rather long, breaking url \url{https://tex.stackexchange.com/questions/731156/the-bottom-margin-of-bibliography-frame-is-too-narrow}.
\enlargethispage{1sp}

\clearpage

\end{document}

Without tagpdf one get the link-level error but then compilation continues and both pages are created. With tagpdf it gives a fatal error which isn't so nice imho:

! Link startet on level 6 ended on level 7.
<argument> ...n {shipout}\__shipout_finalize_box: 
                                                  \cs_set_eq:NN \protect \ex...
l.55 \clearpage
               
? 
! error:  (node lib): lua <node> expected, not an object with type nil
!  ==> Fatal error occurred, no output PDF file produced!

[zauguin]

I'll try to take a look later why we get that error. Can we get

\AddToHook{cmd/@make@specialcolbox/before}{%
  \setbox\@outputbox \vbox {%
    \boxmaxdepth \@maxdepth
    \pdflinkadjustlevel -1\relax
    \unvbox \@outputbox
  }%
}

into pdfmanagement or tagpdf to just avoid the issue completely?

[FrankMittelbach]

@zauguin where is \pdflinkadjustlevel documented?