Cannot extract the property value of ‘DeletedItemCount’

Problem

When querying mailbox statistics in an Exchange organization using the following cmdlet (example) you might receive a warning that the object has been corrupted and it’s in an inconsistent state.

Get-Mailbox USER | Get-MailboxStatistics

WARNING: The object 3d16fdbb-5584-436b-b6c2-ee89adab9b9f has been corrupted, and it's in an inconsistent state. The following validation errors happened:
WARNING: Cannot extract the property value of 'DeletedItemCount'. Source: PropTag(DeletedMsgCount), PropType(Int), RawValue(-11),RawValueType(System.Int32). Target: Type(System.Nullable`1[System.UInt32]), IsMultiValued(False). Error Details: <n/a>

Solution

Check whether the affected mailbox is a regular user mailbox or if the mailbox is in a disconnected state. If the mailbox is disconnected, you can ignore the warning or remove the mailbox from the mailbox store.

If the mailbox is a regular user, check the corresponding identity and move the mailbox to a different database.

Get-Mailbox -Identity 3d16fdbb-5584-436b-b6c2-ee89adab9b9f
Name                      Alias                ServerName       ProhibitSendQuota
----                      -----                ----------       -----------------JohnDoe                   johndoe              MX01             1.8 GB (1,932,735,488 bytes)

Get-Mailbox johndoe | New-MoveRequest -TargetDatabase DB01

Enjoy.