Written by Sam McGeown on 10/8/2010
Published under Microsoft
If you’re having trouble accessing OWA after updating Exchange 2010 with any of the Rollup packages, try this: Uninstall the update package from the Programs and Features control panel Download the package file directly from Microsoft, don’t use Windows Update Open a command prompt or PowerShell prompt as Administrator Navigate to the location of the package (.msp) and run from the elevated command prompt. Apparently when Windows update installs the package it doesn’t run it with the elevated privileges to write to the folder in the Exchange program files – why, I have no idea!