I do not know why, but whenever I try to update the Object Model of an old project we have, Visual Studio 2013 asks if we want to keep version 4 of EF, but even marking the right version it updates and includes references to version 5.
With the old version this does not happen, so much so that today I have used the other version as a palliative measure.
I ask: Is there an explanation for this? Or is it an application bug?
According to the official list of known bugs of Visual Studio 2013 Preview this bug in maintaining the version of the Entity Framework is not included in the list. View list here .
But this may be an error that has not yet been reported (officially). In fact there are still some errors regarding the use of EF in VS2013, as for some people there is no way to generate visual model at times. You can see the full list of Visual Studio related feedbacks (and bugs reported) with the Entity Framework here .
One possible fix is to install the Entity Framework Tools for Visual Studio 2013 or Visual Studio update .
Here is a question about how to force EF4 into Visual Studio 2013 ... and, well, deleting dlls, using T4 ... can help you work around the problem immediately: see question and answer here .
Good luck.
ATTENTION, ADDITIONAL IMPORTANT INFORMATION:
I've been tweeting with Julie Lerman and other fantastic people working with Entity Framework when Jiri Waiting sent us a link on this problem, read here .
I just forgot about this alternative, sorry, but it's simple: install version 4 of the Entity Framework from Nuget.
Visual Studio 2013 already comes with the Nuget Console, you only have to go to it and enter the following code:
Install-Package EntityFramework -version 4.3.0
This will install version 4.3.0 in your project, if you want another version just change the 4.3.0 by the number you want.
This is sure to solve your problem.