Problem Restore EF Core 2.1.1 in VSTS, Hosted VS2017
I also could not restore packages after upgrading to 2.1.1. I got multiple errors similar to this:

Detected package version outside of dependency constraint: Microsoft.AspNetCore.App 2.1.0 requires Microsoft.EntityFrameworkCore (= 2.1.0) but version Microsoft.EntityFrameworkCore 2.1.1 was resolved.


I solved my problem by explicitly specifying version 2.1.301 in the build definition.