No executables found matching command ‘dotnet-aspnet-codegenerator'”

If you’re using csproj (Visual Studio 2017) instead of project.json, then you need to add the following to your csproj file:

    <ItemGroup>
        <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="1.0.1" />
    </ItemGroup>