Can't enable migrations for Entity Framework on VS 2017 .NET Core

EF Core does not have Enable-Migrations command anymore. Migrations are enabled "by default". Add new migration with Add-Migration.

Documentation about package manager commands is here

I had a similar issue with Visual Studio 2017 and a imported project from VS 2015, EF Migrations was no longer working.

After reading through the documentation on GitHub: https://github.com/aspnet/EntityFramework/issues/7031

I installed through Nuget this package:

"Microsoft.EntityFrameworkCore"

It caused a cascade effect of multiple downloads/installs. After the install, and restarting VS 2017, Everything is now back to normal.

Two days later, with another Visual Studio 2015 project, I had the same issue, and resolved it following the above procedure, but then I got this new error:

"Inheritance security rules violated by type: 'System.Net.Http.WebRequestHandler'. Derived types must either match the security accessibility of the base type or be less accessible."

I resolved this error by upgrading the project Framework to the latest ".NET Framework 4.6.2" (Scary.... but it worked without any further issues)

I referred to this documentation on GitHub: https://github.com/dotnet/corefx/issues/11100

I just installed Microsoft.EntityFrameworkCore.Tools, then I tried to execute enable-migrations then I got the following message in VS2017:

Enable-Migrations is obsolete. Use Add-Migration to start using Migrations.

Hope it helps.