i installed EntityFramework.SqlMigrations NuGet Package and i get this error . it worked for me in the past and somehow, now it does not work.
PM> update
After trying everything else, the only way I could get my EntityFramework Migrations commands back was to run the following from the "Package Manager Console":
Import-Module \*PathToSolution*\packages\EntityFramework.5.0.0-beta2\tools\EntityFramework.psd1
After running the above, Add-Migration, Update-Database, etc. was available again.