An instance of analyzer Microsoft.AspNetCore.Mvc.Analyzers.AvoidHtmlPartialAnalyzer cannot be created from C:\

I received the same message after installing dotnet-sdk-2.1.301.

Updating Visual Studio to the latest version (15.7.4) fixed it for me.

This is my simple solution:

Unload Project -> Reload Project -> Rebuild -> Done!

uninstall & installing Nuget of Microsoft.AspNetCore will resolve the issue