Hi Karl, hi Erich

I see this in Debian, too, and it seems to be a regression introduced sometime in October, because the last checkout of packages I made was 30/9 and there was no problem, and with the 31/10 checkout it breaks.

So it seems that something in the graphics inclusion code has changed.

I posted for now on the TL mailing list, hope to see an answer.

Best

Hi Erich - thanks for the report. First, in principle, this is a latex issue, not a tex live issue, so the bug should be reported per https://www.latex-project.org/help/ (last section). Or it may be a distro issue due to the particular version archlinux imported (I cannot guess from its version number what it actually has now), so should be reported to them.

However 1, looking at your uploaded files, there's a discrepancy in that a.tex has the line:
\includegraphics{a_0.pdf}
with an underscore instead of a period. I surmise you just uploaded a different version of the file.

However 2, when I try it, I see no difference in this regard with any version of pdflatex going back several years -- I always get that error message. My understanding is that it is a known deficiency and the workaround is to add \usepackage{grffile}. That is, this document:

\documentclass{article}
\usepackage{grffile,graphicx}
\begin{document}
\includegraphics{a.0.pdf}
\end{document}

(with a trivial ./a.0.pdf) works in all versions I tried, but without grffile, I get what you did, "Unknown graphics extension: .0.pdf". I cannot guess why archlinux pdflatex did not give that error message before.

That's all I know :). Posting to an archlinux or (la)tex forum seems like the best way to pursue, if you wish.

Best,
Karl