I suspect this isn’t exactly a “problem”, just looking for confirmation of what I suspect this error is.
I’ve been assuming the error in the title just means that I would’ve successfully signed a hash but the sector is considered expired now and requires replotting. And once everything is replotted I shouldn’t see the error anymore. Correct?
This might happen in case replotting isn’t quite able to catch up, in that case you’ll see some sectors expiring before they are replaced with an updated version and when node receives corresponding solutions it’ll ignore them.
If this is happening rarely, then I wouldn’t worry too much. Also this will happen less and less frequently over time, see What triggers a sector to start replotting for details
Is it also expected to see this - where the current history size is same as the expiration history size?
Invalid solution received for slot 1553735: SectorExpired { expiration_history_size: HistorySize(21), current_history_size: HistorySize(21) }
Yes, it just expired on on 21, expiration says on which history size it becomes invalid.