PDF export fails with pdflatex and LuaTeX

[Martin Weise]

Dear all,

I am using LyX 2.3.3 on Ubuntu 18.04 (and i have been doing so
(successfully) for almost two years). However, I recently switched
laptops and therefore needed to reinstall ubuntu.

On the new machine, LyX fails to export pdf files via pdflatex and
LuaTeX. There is no pdf file after running export. The only thing that
does work is using ps2pdf.

Here's the message output from Lyx:

***
05:44:25.151: Previewing ...
05:44:25.154: (buffer-view: Ctrl+R)
05:44:25.158: pdflatex  "Document.tex"
05:44:25.232: This is pdfTeX, Version 3.14159265-2.6-1.40.18 (TeX Live
2017/Debian) (preloaded format=pdflatex)
05:44:25.233:  restricted \write18 enabled.
05:44:25.243: entering extended mode
05:44:25.244: (./Document.tex
05:44:25.253: LaTeX2e <2017-04-15>
05:44:25.254: Babel <3.18> and hyphenation patterns for 84 language(s)
loaded.
05:44:25.254:
05:44:25.380: pdflatex  "Bauordnungsamt.tex"
05:44:25.452: This is pdfTeX, Version 3.14159265-2.6-1.40.18 (TeX Live
2017/Debian) (preloaded format=pdflatex)
05:44:25.453:  restricted \write18 enabled.
05:44:25.462: entering extended mode
05:44:25.463: (./Document.tex
05:44:25.464: LaTeX2e <2017-04-15>
05:44:25.465: Babel <3.18> and hyphenation patterns for 84 language(s)
loaded.
05:44:25.466:
05:44:25.593: Successful export to format: PDF
(pdflatex)support/lassert.cpp (51): ASSERTION status != ExportSuccess
VIOLATED IN ../../src/Buffer.cpp:4382
***

Any idea what might be wrong?

Oh yeah... running pdflatex (manually) on LaTeX code produced by LyX 
does work.