Item not sycned because of previous errors.... server replied: Forbidden

Hi support,

One of our users is repeatadly seeing the error 'Item not sycned because of previous errors… server replied: Forbidden. in their Nextcloud sync client log.

Having checked the server logs. Apache’s access.log is returning HTTP 409 842 errors at the same timstamp for a MKCOL operation.

Sync client: for Mac
Nextcloud version: 13

Any ideas on what could have caused this or how to resolve would be appreciated?

Many Thanks,