My guess is that the error occurred while that was being processed, or occurs on the day of renewal, or, something similar.
I am getting the alert that I have reached my Zotero file storage quota.
When I check my settings online, my current plan (6GB) has plenty of space left: 38.3% (2300.9MB) in use.
Zotero is indeed restricting its uploads, however -- I'm finding myself without some file attachments on my laptop, when I go there to check.
Any help resolving it would be appreciated.
You would only get that if 1) you were in a group library owned by somebody else who was at their storage quota (which you're not), 2) you're syncing with a different account, or 3) you added a multi-GB file to your library that would use up the rest of your available space.
If you're not sure which it is, provide a Debug ID for a sync that triggers this and we can take a look.
I am not in any group libraries that I do not own, have only one account, and have not added a file of that size. (Those excellent suggestions were earlier in the thread, and I check for them before posting.)
It has self-resolved. Looking at my account, I noticed that my Zotero storage subscription auto-renewed today. My guess is that the error occurred while that was being processed, or occurs on the day of renewal, or, something similar.
Since I can't replicate it, I won't be able to help highlight if that is what happened, though. Either way, I'm good to go. :D