check the logs

[Wolfgang Engelmann]

I worked today on a document and tried to export is as pdf (Lua-TeX).
I got this message:

The external program
lualatex
finished with an error. It is recommended you fix the cause of the 
external program's error (check the logs).

So I went back to the version of yesterday, in which the export worked.

However, I get the same error.

Very strange!

Where do I find the log file?

I use

Version 2.4.0dev (not released yet)
Built from git commit hash 53ed3dc0
Qt Version (run-time): 5.15.2 on platform xcb
Qt Version (compile-time): 5.15.2
Python detected: python3 -tt

Wolfgang