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


Author: John

John Mueller is a freelance author and technical editor. He has writing in his blood, having produced 99 books and over 600 articles to date. The topics range from networking to artificial intelligence and from database management to heads-down programming. Some of his current books include a Web security book, discussions of how to manage big data using data science, a Windows command -line reference, and a book that shows how to build your own custom PC. His technical editing skills have helped over more than 67 authors refine the content of their manuscripts. John has provided technical editing services to both Data Based Advisor and Coast Compute magazines. He has also contributed articles to magazines such as Software Quality Connection, DevSource, InformIT, SQL Server Professional, Visual C++ Developer, Hard Core Visual Basic, asp.netPRO, Software Test and Performance, and Visual Basic Developer. Be sure to read John’s blog at When John isn’t working at the computer, you can find him outside in the garden, cutting wood, or generally enjoying nature. John also likes making wine and knitting. When not occupied with anything else, he makes glycerin soap and candles, which comes in handy for gift baskets. You can reach John on the Internet at John is also setting up a website at Feel free to take a look and make suggestions on how he can improve it.