Clear PublicFolderDatabase attribute on Mailbox Database


When trying to delete a legacy Public Folder Database from an Exchange 2010 server, I got the following error.

The public folder database ‘X500 Public Folder DB1’ cannot be deleted.

X500 Public Folder DB1
Public folder database “X500 Public Folder DB1” is the default public folder database for the following mailbox database(s):

Before deleting the public folder database, assign a new default public folder database to the mailbox database(s).

Te default public folder database configured for the Mailbox Databases needs to be cleared.

Using the Set-MailboxDatabase cmdlet you can change the PublicFolderDatabase set for a Mailbox Database, however you can’t clear the value.  Public Folders aren’t used anymore in this deployment, therefore changing the public folder database to an alternative database isn’t an option.

Using Set-MailboxDatabase X500DB1 -PublicFolderDatabase $null returns the following error.

Set-MailboxDatabase X500DB1 -PublicFolderDatabase $null
Cannot validate argument on parameter ‘PublicFolderDatabase’. The argument is null or empty. Provide an argument that
is not null or empty, and then try the command again.
+ CategoryInfo : InvalidData: (:) [Set-MailboxDatabase], ParameterBindingValidationException
+ FullyQualifiedErrorId : ParameterArgumentValidationError,Set-MailboxDatabase
+ PSComputerName :


The msExchHomePublicMDB attribute needs to be cleared on the Mailbox Database.

Using ADSIEdit, connect to the Configuration naming content.

Navigate to the Databases container.

  1. CN=Services
  2. CN=Microsoft Exchange
  3. CN=X500 (the name of the Exchange Organization)
  4. CN=Administrative Groups
  5. CN=Exchange Administrative Group (FYDIBOHF23SPDLT)
  6. CN=Databases

Right click on the relevant Mailbox Database (e.g. CN=X500DB1) and edit the properties. 

Find the msExchHomePublicMDB attribute, edit it, clear the value.

Click OK & OK again to save the change.

You should now be able to delete the Public Folder Database.

No msExchHomePublicMDB value showing in ADSIEdit?

Run Get-OrganizationConfig | fl PublicFoldersEnabled

If it’s set to None, this will prevent the attribute being exposed.  Set it back to Local.

Set-OrganizationConfig -PublicFoldersEnabled Local

You can change it back again after the Public Folder Database has been removed.

Set-OrganizationConfig -PublicFoldersEnabled None



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