.NET Core CLI is also an important section in your .NET Core project file. When migrating, you have to upgrade the version of DotNetCliToolReference to 2.0.0, which is shown as follows:

<ItemGroup> 
  <DotNetCliToolReference Include=
  "Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.0" /> 
</ItemGroup> 

There might be more tools added depending on whether you are using Entity Framework Core, User Secrets, and others. You have to update their versions.