The Microsoft.AspNetCore.All package is not supported when targeting .NET Core 3.0 or higher. A FrameworkReference to Microsoft.AspNetCore.App should be used instead, and will be implicitly included by Microsoft.NET.Sdk.Web code example

Example: upgrade .net core 2.2 to 3.1

{
  "sdk": {
    "version": "3.0.100"
  }
}