You may remember my post a while back about issues with applying Exchange 2010 SP1 in situations where you were using Group Policy to control Powershell Execution policies. Specifically, this issue occurs because the Group Policy setting uses the WMI service to enforce the Execution Policy and as part of the Exchange install/upgrade process, the WMI service is stopped, causing the Execution Policy to revert to Restricted and the following error to pop up and the install to fail:

The following error was generated when "$error.Clear();
& $RoleBinPath\ServiceControl.ps1 EnableServices Critical
" was run: "AuthorizationManager check failed.".

Well it turns out that this still applies with Exchange 2010 SP2 in exactly the same fashion.

The (well, A) relevant KB article is here but the “workaround” is a bit half-assed to be honest and you’re much better off just disabling the associated Group Policy setting and configuring the Execution Policy locally (with set-executionpolicy) to either AllSigned,RemoteSigned or Unrestricted for the duration of the upgrade.

Why Microsoft cannot add installer logic to check for this possibility, especially given how long it’s been a potential problem, is beyond me but then I’m not an Exchange developer.