Problems with Exchange 2010 updates

In a recent post, I mentioned a problem with an endpoint mapper (RPC) after the installation of Service Pack 2 for Exchange 2010. It has come to my attention that the reason for this problem is due to a problem with the initial installation. The problem happened again in the same Exchange environment during a Rollup 2 installation which lead me to investigate the Exchange Setup logs further. In the file UpdateCAS.log the following entry was logged.

The line reads "Error updating OWA/ECP: The term 'Get-ExchangeServer' is not..." which indicated a problem with the Exchange Management Shell (PowerShell) commands. After browsing around the configuration I noticed that some entries were missing from the registry compared to another Exchange server.

A quick fix for this problem was simply to export the PowerShellSnapIns key from a working Exchange server and import the difference to the faulty one. The question to why these keys are missing in the first place still remains unanswered. However, we're one step closer to the truth.