Public Folders stopped synching with Outlook on multiple tenants with Exchange online.

Occasional Contributor

Since about 1/3/2022 all of our customers are getting sync errors when syncing public folders.


New data stops synching, and edit do not come over. It appears the header is updating but not the full item


We have also found that online public folders are only showing the headers changing and we think this is why the folder gets a sync error.


Scenario: Create a new public folder (or use an existing one)

Create a new post item

All users see the item

Change the subject of the item. It appears the first change comes through.

Change the subject again.

You see the header update but not the item.

Change the subject again.

Other users start getting a sync error.  Items do not update, and new item do not come down.


We run diagnostics on the Public folder mailbox and get an error "Message:Failed to sync public folder hierarchy. Resource 'Processor' is unhealthy and shouldn't be accessed."



Get-PublicFolderMailboxDiagnostics CRM -IncludeHierarchyInfo





                        [Message:Failed to sync public folder hierarchy. Resource 'Processor' is unhealthy and shouldn't be accessed.


Anh help would be appreciated. We have had a ticket open with Exchange online since 1/12/2022 but have been disappointed as they appear to not be able to help and do not seem to have an escalation method to the Exchange Team.

1 Reply
best response confirmed by Gary Cawley (Occasional Contributor)
Looks like it was fixed with Exchange advisory EX316697, Exchange Online 2/14/2022