A synthetic filelist tries to give you a synthetic backup version that’s the past one plus whatever made it before interruption of next backup, but that’s arguably unessential if next good backup is close enough.
Warning Message after Backup is my explanation for why message expects a dblock instead of a dlist, which is what represents files in a version. It’s a bad lookup. I’d like a great test case, but don’t have it.
Warning: Expected there to be a temporary fileset for synthetic filelist #2329 is closed. Need new issue.
Back to the primary issue, this is adding fuel to the theory that this particular unfortunate ending (which is arguably a bug in itself), is a follow-on error to some other issue. Maybe we also need a test case for this. Sometimes details obscure overall picture, e.g. visible using About --> Show log --> Live --> Retry which would probably have shown –number-of-retries retries before giving up then taking error paths…