You also need to say where to log to. This isn’t the regular job log here.
Retry level is a fairly light log. I hope we don’t need to go super-detailed such as seeing all the SQL.
That might give a very nice view of the exact UPDATE that got the constraint failure, but log is huge.
Let’s not go there unless lighter logging doesn’t give us the answer, if the constraint failure reoccurs.
Your less-than-fatal retry situation is a different worry. Retries are OK. Acceptance then loss is not…
Feature Request: PCloud backup #4337 is (like so many others) awaiting volunteer developer work, however it gives some worrisome comments about pCloud WebDAV, and a possible rclone solution.