Exchange 2010 SP2 Rollup 5 V2 today (KB2785908) keeps failing regardless of whether I try installing using Microsoft Update (fails with error 80070643) or the download ("Setup ended prematurely because of an error.")
Event Viewer has this to say ... Product: Microsoft Exchange Server - Update 'Update Rollup 5-v2 for Exchange Server 2010 Service Pack 2 (KB2785908) 14.2.328.10' could not be installed. Error code 1603. Windows Installer can create logs to help troubleshoot issues with installing software packages. Use the following link for instructions on turning on logging support: http://go.microsoft.com/fwlink/?LinkId=23127
Server has all roles and is current up to SP2ru5.
Here is the Windows Installer log: https://skydrive.live.com/redir?resid=E590E0F619452189!9683&authkey=!AB1zXR5c7Sk3lF0