Recently in the testing project when installing Entity Framework with following command with NuGet management console:
Install-Package EntityFramework -projectname SportsStore.Domain
The installation failed with following message:
Attempting to resolve dependencies for package ‘EntityFramework.6.1.3’ with DependencyBehavior ‘Lowest’
Resolving actions to install package ‘EntityFramework.6.1.3’
Resolved actions to install package ‘EntityFramework.6.1.3’
Adding package ‘EntityFramework.6.1.3’ to folder ‘C:\git\SportsStore\packages’
Added package ‘EntityFramework.6.1.3’ to folder ‘C:\git\SportsStore\packages’
Added package ‘EntityFramework.6.1.3’ to ‘packages.config’
Executing script file ‘C:\git\SportsStore\packages\EntityFramework.6.1.3\tools\init.ps1’
Executing script file ‘C:\git\SportsStore\packages\EntityFramework.6.1.3\tools\install.ps1’Type ‘get-help EntityFramework’ to see all available Entity Framework commands.
Successfully installed ‘EntityFramework 6.1.3’ to SportsStore.Domain
Install failed. Rolling back…
Removed package ‘EntityFramework 6.1.3’ from ‘packages.config’
Removing package ‘EntityFramework 6.1.3’ from folder ‘C:\git\SportsStore\packages’
Access to the path ‘C:\git\SportsStore\packages\EntityFramework.6.1.3\tools\EntityFramework.PowerShell.Utility.dll’ is denied.
Access to the path ‘EntityFramework.PowerShell.Utility.dll’ is denied.
Removed package ‘EntityFramework 6.1.3’ from folder ‘C:\git\SportsStore\packages’
Install-Package : An item with the same key has already been added.
At line:1 char:1
+ Install-Package EntityFramework -projectname SportsStore.Domain
+ CategoryInfo : NotSpecified: (:) [Install-Package], Exception
+ FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PackageManagement.PowerShellCmdlets.InstallPackageCommand
One or more packages could not be completely uninstalled: ‘C:\git\SportsStore\packages\EntityFramework.6.1.3’. Restart Visual Studio to finish uninstall.
After google around for a while it turned out that it is the NuGet itself is causing the problem, although the error message seems otherwise. After download and install NuGet Package Manager for Visual Studio 2015, the problem got resolved.