ObjectClass Unknown is returned when you use the Get-MailboxStatistics cmdlet

• Applies to:

  Exchange Online, Exchange Server 2016 Enterprise Edition, Exchange Server 2016 Standard Edition, Exchange Server 2013 Enterprise, Exchange Server 2013 Standard Edition

Original KB number:   2795291

Problem

When you use the Get-MailboxStatistics Windows PowerShell cmdlet to get information about a mailbox in on-premises Exchange Server or Exchange Online in Microsoft 365, the ObjectClass property unexpectedly returns a value of Unknown.

For example, when you run the Get-MailboxStatistics admin | FL *object* command, you receive the following output:

ObjectClass : Unknown
ObjectState: Unchanged

In earlier versions of Exchange Server and in Exchange Online in Microsoft 365, the ObjectClass property returns the correct value. For example, this property returns Mailbox for user mailboxes and Mailbox, Disabled for equipment and room mailboxes.

More information

Still need help? Go to Microsoft Community.