Comment 2 for bug 1488411

Thank you for your support. No - reboot nor "sudo pkill -fe backintime ; sudo pkill -fe pw-cache" helps.

This is what strace says before nothing happens and a few seconds later the timeout occurs:

wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 4674
stat("/usr/local/sbin/ssh-agent", 0x7ffc0c10bd40) = -1 ENOENT (No such file or directory)
stat("/usr/local/bin/ssh-agent", 0x7ffc0c10bd40) = -1 ENOENT (No such file or directory)
stat("/usr/sbin/ssh-agent", 0x7ffc0c10bd40) = -1 ENOENT (No such file or directory)
stat("/usr/bin/ssh-agent", {st_mode=S_IFREG|S_ISGID|0755, st_size=284784, ...}) = 0
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fd1845daa10) = 4675
wait4(-1,
Back In Time
Version: 1.1.7.8

Maybe it's due to some missing/additional package? I will try to investigate further the difference compared to a fresh installed Cinnamon VM.