I also have a synchronisation error. I don't know what it is. I just get an exclamation mark next to the synchronisation icon (top right). When I click on it, there is no error message, just the option to send a report... Report ID 700773506
Ah! I just noticed that the incidence of this error coincides with a notification from my virus protection package (Sophos) that it has blocked a threat from 'Mal/DrodZp-A'. Apparently a Zotero file has got a virus in it and the virus protection is stopping it from being saved? Is it one of my files or one of yours?
It's just something in one of your web page snapshots. You can search in Zotero for the 8-character string from the filename ("8D65JNGK") in All Fields & Tags mode, delete the attachment, and empty the trash.
The item key (8-character string) is listed in the error message I quoted above, which is from your error report. When Zotero syncs files, they're first saved as tmp/[item key].zip before being moved to storage/[item key].
I did as you advised and it seems to have fixed the problem -- I can now do a (manual) sync without getting the virus notification. Thank you. :-)
I presume you used some method of identifying the offending file that is not available to me?