How to repair a corrupted Public Folder (on-prem)

Question

Hello guys,

Hope all is well.

In our Exchange 2019 environment we use Public Folders extensively. Everything seems ok except one of folders that looks corrupted.

I can execute commands Get-PublicFolder / Set-PublicFolder against it, I can get its items statistics (Get-PublicFolderItemStatistics) and have access to items through Outlook. But commands Get-PublicFolderStatistics, Get-PublicFolderClientPermission return the same error:

The security principal specified is already on the permission set.
    + CategoryInfo          : NotSpecified: (:) [Get-PublicFolderStatistics], CorruptDataException
    + FullyQualifiedErrorId : [Server=E7,RequestId=b2f89187-878f-4cab-b05f-fcdaa7d82c0d,TimeStamp=2/17/2025 3:19:42 PM] [FailureCategory=Cmdlet-CorruptDataException] B960021F,Microsoft.Exchange.Manag
   ement.MapiTasks.GetPublicFolderStatistics

I tried to repair the corresponding public folder mailbox (New-MailboxRepairRequest) but none of my requests found errors. I moved the public folder content to a different public folder mailbox, no success.

Any ideas how to fix the issue? My guess is that ACL list of the public folder is corrupted.

Answer 1

Hi,@StefanoC

Thanks for posting your question in the Microsoft Q&A forum.

It looks like the issue might indeed be related to the Access Control List (ACL) for that specific public folder.

1.You can remove and re-add permissions: Manually remove and re-add the permissions for the public folder to potentially rectify any corruption.

Use the following command to remove a specific user’s permissions:

Remove-PublicFolderClientPermission -Identity "\YourProblematicFolder" -User "UserWithIssues"

Then re-add the permissions:

Add-PublicFolderClientPermission -Identity "\YourProblematicFolder" -User "UserWithIssues" -AccessRights <AccessRight>

Repeat this for all users who have permissions on the folder.

2.If the above steps do not resolve the issue, you can try exporting the data, deleting the public folder, and then re-creating it.

• Export the contents to a PST file:

    New-MailboxExportRequest -Mailbox <PublicFolderMailbox> -PublicFolder “\YourProblematicFolder” -FilePath \\Path\To\Export\File.pst
  

• After the export completes, remove the public folder:

    Remove-PublicFolder -Identity "\YourProblematicFolder"
  

• Recreate the public folder and import the data back:

    New-PublicFolder -Name "YourProblematicFolder"
  

• Then import the PST:

    New-MailboxImportRequest -Mailbox <PublicFolderMailbox> -FilePath \\Path\To\Export\File.pst
  

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