Created attachment 6483
> gdb backtrace attached - it is strange that the
> thunar_file_compare_by_name() function is called even for only one file in
> working directory - both file_a->collate_key_nocase and
> file_b->collate_key_nocase are NULL. I noticed that sometimes this function
> is not called, but when it is (it is random), then it crashes.
This is probably related to threading issues and timing-specific. Something needs to be protected to avoid being accessed when it shouldn't be. Likely the old file is in the process of being destroyed while being compared with the new file or something like that.
Does the attached workaround prevent the crashes? It is not a proper fix we can apply, but until we have a good solution it could help.