Exception raised when I'm trying enable migrations in EF 4.3.1

Question

I'm using Entity framework 4.3.1 installed by nuget in my .Net 4.0 class library project. In situation, when I call the "Enable-Migrations" command in PM console, I receive following exception:

Exception calling "LoadFrom" with "1" argument(s): "Nelze načíst soubor nebo sestavení file:///D:\ Users\DvoracekR\Documents\Visual Studio 2010\Projects\WebCameras\packages\EntityFramework.4.3.1\to ols\EntityFramework.PowerShell.Utility.dll nebo jeden z jejich závislých prvků. Systém nemůže nalé zt uvedený soubor." At D:\Users\DvoracekR\Documents\Visual Studio 2010\Projects\WebCameras\packages\EntityFramework.5. 0.0-rc\tools\EntityFramework.psm1:393 char:62 + $utilityAssembly = [System.Reflection.Assembly]::LoadFrom <<<< ((Join-Path $toolsPath Entity Framework.PowerShell.Utility.dll)) + CategoryInfo : NotSpecified: (:) [], MethodInvocationException + FullyQualifiedErrorId : DotNetMethodException

You cannot call a method on a null-valued expression. At D:\Users\DvoracekR\Documents\Visual Studio 2010\Projects\WebCameras\packages\EntityFramework.5. 0.0-rc\tools\EntityFramework.psm1:394 char:50 + $dispatcher = $utilityAssembly.CreateInstance <<<< ( + CategoryInfo : InvalidOperation: (CreateInstance:String) [], RuntimeException + FullyQualifiedErrorId : InvokeMethodOnNull

Exception calling "CreateInstanceFrom" with "8" argument(s): "Typ System.Data.Entity.Migrations.En ableMigrationsCommand ze sestavení EntityFramework.PowerShell, Version=4.3.1.0, Culture=neutral, P ublicKeyToken=b77a5c561934e089 nelze načíst." At D:\Users\DvoracekR\Documents\Visual Studio 2010\Projects\WebCameras\packages\EntityFramework.5. 0.0-rc\tools\EntityFramework.psm1:418 char:31>+ $domain.CreateInstanceFrom <<<< ( + CategoryInfo : NotSpecified: (:) [], MethodInvocationException + FullyQualifiedErrorId : DotNetMethodException

Answer 1

I solved problem described above.

1. I uninstalled Entity framework using NuGet package manager.
2. I manually cleared subdirectories started with "Entity" in packages directory.
3. I installed Entity Framework 4.3.1 again

Now migrations are enabled correctly.

Answer 2

I know this is an old question and already has an accepted answer, but I had this issue and thought I'd share what I did to resolve it.

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My solution was in source control and I had messed up my local project. I decided to start over from Source Control, so I created a new folder and Checked out the code from SVN.

When I did, I was no longer able to create migrations. I got the same error listed above. I tried Uninstall-Package EntityFramework, but got a similar message about missing files/references within EntityFramework.

I went back to my old folder and looked in $Project\packages\EntityFramework.6.0.2\ and compared this to my new folder. There were several DLLs/Xml files missing because they were not in Source Control. They were in the \tools\ , \lib\net40 and \lib\net45\ directories.

I just copied these files to my new project, closed/reopened Visual Studio, and did a Rebuild. After that, everything was working fine.

Answer 3

Reinstalling the NuGet package didn't work for me. What did work was to move the project from a network drive to a local drive. Running a compare showed that, apart from obj and bin directories, all files were binary identical.

If I remember correctly, my last attempt at Update-Database was before I moved the project to a network drive.