The Entity Framework and Visual Studio 2012 Update 1

It’s common practice for me to wait a day or two and then look for potential problems with an update before I install it. I don’t have a fleet of machines with which to test updates and an errant update could put me out of business until I can correct it. I let Visual Studio 2012 Update 1 languish for a while because I’m in the midst of a book project with it (Entity Framework Development Step by Step) and wanted to wait until I reached a point where the update wouldn’t affect my scheduled writing time. A cursory look online didn’t point out any problems with the update. However, after installing Update 1 I suddenly began receiving this message every time I tried to perform an update of my Entity Framework model:

A processor named ‘T4VSHost’ could not be found for the directive named ‘CleanupBehavior’.

The odd thing is that I had tried a number of other tasks and completed them without problem with the update in place. So, this issue took me by surprise. Even more interesting is that there doesn’t seem to be a major outpouring of angst online about the issue—leading me to believe that many developers are only now moving to Visual Studio 2012. I did find a Microsoft Connect discussion about the issue, which includes feedback from Microsoft about the problem. This problem apparently first appeared as part of the Community Technical Preview (CTP) release. It appeared to be fixed during that release, so Microsoft closed the error. However, look down the list of comments and you see that on 3/5/2013 Microsoft reopened the issue.

The Microsoft Connect discussion also presents two workarounds—neither of which worked for me. I finally ended up uninstalling my copy of Visual Studio 2012 completely, ensuring that the directory and everything else associated with Visual Studio 2012 that I could find were removed from the system, and reinstalling Visual Studio 2012 sans Update 1 to get my system back into an operational state.

The bottom line is that I can’t recommend installing Update 1 if you plan to work with the Entity Framework using Visual Studio 2012. In fact, it may be a good idea if you hold off installing Update 1 until Microsoft has more time to work out the kinks. Don’t get me wrong. Installing updates is an important part of keeping your system running well and keeping the crackers at bay, but this is one time where the update fails to live up to its promise. Let me know whether you’ve experienced this particular issue at