Hello Orogor:
Thanks for your thoughts.
I didn’t logout or kill any processes between encountering the error in the log, and the urbackupclientbackend process is running as root user - so I don’t see that it should have any permissions problems accessing this folder, and I don’t see why the folder wouldn’t have existed one moment and then existed the next.
I’ve tried the backup a number of times - and it fails on this folder each time - but only on macOS 10.13.
Even if the folder is somewhat ephemeral, is it right that this stops the backup of the rest of the filesystem?
Thanks,
Pants.