The term ‘Add-migration’ is not recognized – VS2017 and EntityFrameworkCore

The solution that worked for me after trying a whole raft of other solutions posted, was to:

• right click on my project
• select Manage Nuget Packages
• select the browse tab
• thick Include prerelease check box
• install the Microsoft.EntityFrameworkCore.Tools

N.b that aspnetcore project in visual studio 2017 do not seem to have the project.json file.