Back in June 2011 we released a CTP called “Microsoft Entity Framework June 2011 CTP”. We were excited by all the features (enums, support for spatial types, TVFs, auto-compiled queries etc.) included in this preview and people were excited to try them. Unfortunately shipping a component that is part of .NET Framework outside the .NET Framework turned out to be challenging. This resulted in a number of tricks like the beloved😉 by everyone “Microsoft Entity Framework June 2011 CTP” target or publisher’s policies with binding redirects and the experience was far from perfect (e.g. uninstalling Microsoft Entity Framework June 2011 CTP will break tools as noted in the Readme). Now this release is haunting people. We investigated a number of issues where the root cause of the problem was presence of this CTP on the machine. The issues are popping up out of nowhere and it may be hard to figure out what’s going on. Some of them are – Migrations not working correctly (http://stackoverflow.com/questions/9860097/ef-5-vs-11-error-when-doing-add-migration), MissingMethodExceptions (http://stackoverflow.com/questions/9591929/can-anyone-spot-why-i-keep-getting-this-error-testing-the-ef-5-beta) , Visual Studio 11 Beta crashing (this is actually another flavor of MissingMethodException but you probably won’t even see it without WinDbg). Why this happens? The .NET Framework 4.5 is an in-place update. Microsoft Entity Framework June 2011 CTP installed binding redirect to redirect calls to System.Data.Entity.dll 220.127.116.11 to System.Data.Entity.dll 18.104.22.168. This redirect *will still work* if you install .NET Framework 4.5 (be it Beta, RC or RTM). This is bad as there were quite a few changes we added after the June CTP was shipped and dependencies were taken on these changes (e.g. EF Designer). Once .NET Framework 4.5 Beta shipped there is not any benefit of having the CTP – what’s in CTP is in .NET Framework 4.5 Beta, the CTP does not come with any support (as opposed to .NET Framework 4.5 Beta), the CTP does not have a “go-live” license (as opposed to .NET Framework 4.5 Beta and Entity Framework 5 Beta). Even though I believe Microsoft Entity Framework June 2011 CTP was a very useful release *it’s time to move on and uninstall it*. You can find instructions here: http://blogs.msdn.com/b/adonet/archive/2011/06/30/announcing-the-microsoft-entity-framework-june-2011-ctp.aspx.