After the co-exist with Exchange 2007 and Exchange 2010 had worked fine for a while I wanted to remove the Exchange 2007 servers.
No problems with removing CAS server. But when removing the mailbox role was not as easy as I thought it would be. When I had replicated all the public folders, and runned MoveAllReplicas.ps1, I checked with Get-PublicFolderStatistics. No folders listed! But when I tried to delete the Public Folder database I got the following error message:
Microsoft Exchange Error
The public folder database ‘Public Folder Database’ cannot be deleted.
Public Folder Database
Object is read only because it was created by a future version of Exchange: 0.10 (18.104.22.168). Current supported version is 0.1 (8.0.535.0).
I also tried to remove it trough EMS.
Solution: Remove it from Exchange 2010 EMS. I used following command: Get-PublicFolderDatabase – Server “nameofserver” | Remove-PublicFolderDatase