Server consistently crashes

Interesting portion of server log is:
2018-11-18 11:23:37: ursule: Linking unchanged and loading new files…
2018-11-18 11:23:37: Referencing snapshot on “ursule” for path “root” failed: FAILED
2018-11-18 11:46:44: Starting HTTP-Server on port 55414
2018-11-18 11:46:44: HTTP: Server started up successfully!
Version of server is 2.2.11.2193, and the crash is reproducible every time I start an incremental backup of “ursule”.
I should add that filesystem of path “root” is ext4, and there is no snapshot mechanism on top of it.
Any help appreciated, thanks.

A crash backtrace would be helpful. Please see here for instructions https://urbackup.atlassian.net/wiki/spaces/US/pages/8323075/Debugging+with+gdb+on+Linux

Got the suggestion, thanks. Maybe I can spare some time on that next weekend.
I already did the compile and docker-ization myself for arm64, so I think I can handle those instructions.
Keep the good work!

Ok, because it is arm64 the actual signal (in e.g. dmesg) would be interesting.

I skipped the backups of the aarch64 machine for a while. Every once in a while I tried again, and eventually the backup worked out till the end! I guess it was related to deduplication stuff (and the existing backups having changed in the meantime). Thanks for the answers and sorry for the noise. I’ll try to improve my reporting of any following bugs.