Just ran across a issue when creating a new ASP.NET Core project and upgrading to the 1.1.0 Nuget packages. When trying to build I would get this error:

To resolve I opened the project.json and found in the dependencies:

“Microsoft.NETCore.App”: “1.1.0”,

and change to:

“Microsoft.NETCore.App”: { “version”:  “1.1.0”, “type”: “platform”}