Updates at end
After an extremely painful update process largely because PDF export uses XeLaTeX and I have always preferred LaTeX, so different packages needed)...
(Important aside: I think pandoc expects to find everyshi.sty in package MS, but as reported on CTAN it's no longer in that package)
PDF creation fails with this info from the server:
notebook.tex:1678: Unable to load picture or PDF file '
dvipdfmx:fatal: Image inclusion failed for "attachment:9e002d53-d7a5-42e1-8b51-0fdec8f4dad5.png".
No output PDF file written.
Sorry, but xelatex did not succeed.
The log file hopefully contains the information to get MiKTeX going again:
C:\Users\usernamehere\AppData\Local\MiKTeX\2.9\miktex\log\xelatex.log
The xelatax.log shows:
2021-06-10 08:02:26,620+0100 INFO xelatex.core - start process: miktex-dvipdfmx.exe --miktex-enable-installer -q -E -o notebook.pdf
2021-06-10 08:02:28,594+0100 FATAL xelatex.core - Invalid argument
2021-06-10 08:02:28,594+0100 FATAL xelatex.core - Function: fwrite
2021-06-10 08:02:28,594+0100 FATAL xelatex.core - Result: 22
2021-06-10 08:02:28,594+0100 FATAL xelatex.core - Data: <no data>
2021-06-10 08:02:28,594+0100 FATAL xelatex.core - Source: Libraries\MiKTeX\TeXAndFriends\include\miktex/C4P/C4P.h:646
2021-06-10 08:02:28,594+0100 FATAL xelatex - Invalid argument
2021-06-10 08:02:28,594+0100 FATAL xelatex - Info:
2021-06-10 08:02:28,594+0100 FATAL xelatex - Source: Libraries\MiKTeX\TeXAndFriends\include\miktex/C4P/C4P.h
2021-06-10 08:02:28,594+0100 FATAL xelatex - Line: 646
2021-06-10 08:02:28,596+0100 INFO xelatex - this process (37528) finishes with exit code 1
And if we then look in miktex-dvipdfmx.log we find the other end of the call...
2021-06-10 08:02:26,808+0100 INFO miktex-dvipdfmx - this process (4364) started by 'xelatex' with command line: miktex-dvipdfmx.exe --miktex-enable-installer -q -E -o notebook.pdf
2021-06-10 08:02:28,558+0100 ERROR miktex-dvipdfmx - Image inclusion failed for "attachment:9e002d53-d7a5-42e1-8b51-0fdec8f4dad5.png".
2021-06-10 08:02:28,559+0100 INFO miktex-dvipdfmx - this process (4364) finishes with exit code 1
So. Image inclusion failed for the png, which is is an attachment in a markdown cell (a screen grab of previous output so that long-running code doesn't always have to be re-run).
Can anyone confirm this should work (I have seen something, somewhere that there was an issue with images in markdown cells a long time ago) and if so, explain how to resolve this issue?
Update I 29/06/2021
From the xelatex log: there's an "invalid argument message" and the arguments "-q -E -o" just above are for miktex-dvipdfmx.exe, but referring to the dvipdfmx manual I can't find the -q, -o arguments...
Then checking the BASIC manual for dvipddf () and options there -o is the output filename (not a great surprise) but still no sign of a -q option.
That is at least consistent, but... what? How? etc. etc. etc.
Update II of 29/06/2021
Updated miktex; found a new item, miktex-dvipdfmx-bin-x64-2, has been installed! Re-ran notebook export. Different error:
nbconvert failed: PDF creating failed, captured latex output:
Failed to run "xelatex notebook.tex -quiet" command:
notebook.tex:561: Undefined control sequence
checking the miktex-dvipdfmx.log I find
2021-06-10 08:02:26,808+0100 INFO miktex-dvipdfmx - this process (4364) started by 'xelatex' with command line: miktex-dvipdfmx.exe --miktex-enable-installer -q -E -o notebook.pdf
2021-06-10 08:02:28,558+0100 ERROR miktex-dvipdfmx - Image inclusion failed for "attachment:9e002d53-d7a5-42e1-8b51-0fdec8f4dad5.png".
2021-06-10 08:02:28,559+0100 INFO miktex-dvipdfmx - this process (4364) finishes with exit code 1
So the argument error was (presumably) resolved by the use of miktex-dvipdfmx-bin-x64-2, and now there's some other issue in the tex itself
Unfortunately, a full search of C:\ and the separate documents drive fails to find notebook.tex so investigation dead-ends here.
However, note that PDF export works OK for a notebook without embedded "attachments" - I wonder whether it simply can't find the attachment "files"
Final error report from jupyter as 500 server error:
nbconvert failed: PDF creating failed, captured latex output:
Failed to run "xelatex notebook.tex -quiet" command:
notebook.tex:496: Undefined control sequence [17 times]
...
notebook.tex:2119: Unable to load picture or PDF file '
dvipdfmx:fatal: Image inclusion failed for "attachment:9e002d53-d7a5-42e1-8b51-0fdec8f4dad5.png".
No output PDF file written.
Sorry, but xelatex did not succeed.
The log file hopefully contains the information to get MiKTeX going again:
C:\Users\Julian\AppData\Local\MiKTeX\2.9\miktex\log\xelatex.log
And the xelatex log says there was no data
2021-06-29 08:30:42,590+0100 INFO xelatex.core - start process: miktex-dvipdfmx.exe --miktex-enable-installer -q -E -o notebook.pdf
2021-06-29 08:30:43,984+0100 FATAL xelatex.core - Invalid argument
2021-06-29 08:30:43,984+0100 FATAL xelatex.core - Function: fwrite
2021-06-29 08:30:43,984+0100 FATAL xelatex.core - Result: 22
2021-06-29 08:30:43,984+0100 FATAL xelatex.core - Data: <no data>
2021-06-29 08:30:43,984+0100 FATAL xelatex.core - Source: Libraries\MiKTeX\TeXAndFriends\include\miktex/C4P/C4P.h:646
2021-06-29 08:30:43,984+0100 FATAL xelatex - Invalid argument
2021-06-29 08:30:43,984+0100 FATAL xelatex - Info:
2021-06-29 08:30:43,984+0100 FATAL xelatex - Source: Libraries\MiKTeX\TeXAndFriends\include\miktex/C4P/C4P.h
2021-06-29 08:30:43,984+0100 FATAL xelatex - Line: 646
2021-06-29 08:30:43,986+0100 INFO xelatex - this process (38968) finishes with exit code 1
Possibly related: github nbconvert issues