title: AspNetCore:2.1 not found
body: <p>Created a new .NET CORE 2.1 (preview) web app. Running it in local docker with Linux container
  I am getting compiler error:</p>
  
  <p>Error Building blobtest<br>
  Service 'blobtest' failed to build: manifest for microsoft/aspnetcore:2.1 not found.  </p>
  
  <p>My dotnetversion<br>
  C:\WINDOWS\system32>dotnet --version
  2.1.300-preview2-008530</p>