Hi,
we have the exact same error, but the provided workaround doesn't helps:
https://support.plesk.com/hc/en-us/articles/360010965519--BUG-Multiple-errors-in-Apache-error-log-file-from-Plesk-client-denied-by-server-configuration-usr-share-plesk-service-localdomain-
Was anybody able to solve this...