This issue occurs in a Microsoft Exchange Server 2013 environment that has the UM Language Pack installed. A cumulative update installation removes the UM language pack before it continues the server upgrade. Additionally, if the log level for the MSExchange Management Application\ComponentInfoBasedTask event logging category in Exchange Server diagnostic logging is High or Expert, Exchange server 2013 cannot upgrade, and the following error message is displayed in the ExchangeSetup.log file:
Setup will run the task 'remove-umlanguagepack' Setup launched task 'remove-umlanguagepack -DomainController 'dc1.contoso.com' <…>' [ERROR] Object reference not set to an instance of an object. [WARNING] An unexpected error has occurred and a Watson dump is being generated: Object reference not set to an instance of an object.
This issue occurs because the initialization of internal PowerShell objects fails in some setup scenarios.