If you find as I did that EF is not installed in the Gac then the next step is to uninstall it AFTER you note the version of your package. I use NuGet so I went to Tools…Library Package Manager…Package Manager Console. I tried the GUI first but uninstalling failed and as of this writing you can only install the latest version of the package.
- Open your solution and go to Tools…Library Package Manager…Package Manager Console
- Select the project that uses EF and is having the problem
- Type Uninstall-package EntityFramework
- You should be prompted to restart Visual Studio so close and reopen VS and your solution
- Open Package Manager Console with Tools…Library Package Manager…Package Manager Console
- Type Install-package EntityFramework (add -Version x.x.x if you’re installing an older version)
- You should be good to go