Exchange 2010 / 2013 – Couldn’t resolve the user or group 19

Exchange 2010 / 2013 - Couldn't resolve the user or group
When you’re upgrading Exchange 2010 to a higher Service Pack ¬†or when installing Exchange 2013, you can find yourself getting the following error when the mailbox role is being installed. This can be during any of the Exchange 2010 Service Pack installations, so Exchange 2010 SP1, Exchange 2010 SP2, Exchange 2010 SP3 or during an ...