Please have a look at the server log file (see Having problems with UrBackup? Please read before posting ).
Also this would be helpful: https://urbackup.atlassian.net/wiki/spaces/US/pages/8323075/Debugging+with+gdb+on+Linux The OpenSUSE Ubuntu builds have debug symbols i.e. http://download.opensuse.org/repositories/home:/uroni/xUbuntu_18.04/amd64/