On trying to upgrade to service pack 2 for MSForeFront TMG (Threat Management Gateway), I repetitively got the below error:
“The upgrade patch cannot be installed by the windows Installer service beause the program to be upgraded may be missing, or the upgrade patch may update a different version of the program. Verify that the program to be upgraded exists on your computer and that you have the corect upgrade patch.”
This one has me beaten for a while. I had already upgraded to SP1 for TMG, and I couldn’t see why upgrading to SP2 wouldn’t work. Furthermore, in recent years Microsoft have generally allowed you to jump service packs anyway (such as going to a Service Pack 2, whilst still having the original RTM of a given product).
I dug around a bit, and found there is an interim update for TMG, post SP1, that must be installed to install SP2. This update (unsurpisingly named “Software Update 1 for Microsoft Forefront Threat Management Gateway (TMG) 2010 Service Pack 1”) can be found here.
Install this, then try running the SP2 for TMG update again. You should find it all goes well.