How to fix this error about entity framework "Running transformation: Could not load file or assembly 'EntityFramework.SqlServer, Version=6.0.0.0"?

I'm trying to update and even uninstalling and then again install various versions of entity framework to resolve this error but its continuously showing the same error.

Severity Code Description Project File Line Suppression State Error Running transformation: Could not load file or assembly 'EntityFramework.SqlServer, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. Strong name signature could not be verified. The assembly may have been tampered with, or it was delay signed but not fully signed with the correct private key. (Exception from HRESULT: 0x80131045) WebApplication9 C:\Users\howdy\Source\Repos\WebApiFirst\WebApplication9\WebApplication9\Model1.edmx 57