"..the server announced it should have been 1B." - but which file?

Got a new laptop. Everything synced fine, except Nextcloud sync client says:

“The downloaded file is empty despite that the server accounced that it should have been 1 B. Readme.md”

The problem is I have thousands of Readme.md files, and the sync client does not tell me which one it is. It’s not possible to click the notification to go to the file in question, and I have no idea what the problem is.