Implicit selection of `Microsoft.AspNetCore.App` broken in new SDK

When we upgraded to the new SDK (3.0.100-preview-009730) we started experiencing the following errors in our templating tests:

C:\Users\rybrande\.nuget\packages\microsoft.aspnetcore.app\2.1.0\build\netcoreapp2.1\Microsoft.AspNetCore.App.targets(14,5): error : This version of Microsoft.AspNetCore.App is only compatible with the netcoreapp2.1 target framework. Please target netcoreapp2.1 or choose a version of Microsoft.AspNetCore.App compatible with netcoreapp3.0.

I’ve created a minimal repro of this issue here. You can work around this by explicitly giving the version of Microsoft.AspNetCore.App as Version="3.0.0-alpha1-10653", but it’s my understanding that the implicit scenario is not only supported, but the recommended path.

If you’d like to see it in the “real” environment the repro steps against Templating are as follows:

1. Acquire SDK version 3.0.100-preview-009730.
2. git clone https://github.com/aspnet/Templating
3. ./run.ps1 -update upgrade deps
4. ./build.cmd Observe the test failures.

dotnet --info:

.NET Core SDK (reflecting any global.json):
 Version:   3.0.100-preview-009730
 Commit:    6a33a587e8

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.17763
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Users\rybrande\.dotnet\x64\sdk\3.0.100-preview-009730\

Host (useful for support):
  Version: 3.0.0-preview1-26907-05
  Commit:  96537a8f64

.NET Core SDKs installed:
  2.1.403 [C:\Program Files\dotnet\sdk]
  2.1.500-preview-009398 [C:\Program Files\dotnet\sdk]
  2.2.100-preview2-009404 [C:\Users\rybrande\.dotnet\x64\sdk]
  2.2.200-preview-009431 [C:\Program Files\dotnet\sdk]
  3.0.100-preview-009730 [C:\Users\rybrande\.dotnet\x64\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.2.0-preview2-35157 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.0-preview3-35364 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 3.0.0-alpha1-10620 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 3.0.0-alpha1-10663 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.2.0-preview2-35157 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.0-preview3-35364 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-alpha1-10620 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-alpha1-10663 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-alpha1-10706 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.AspNetCore.App]
  Microsoft.DesktopUI.App 3.0.0-alpha-27030-3 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.DesktopUI.App]
  Microsoft.NETCore.App 2.2.0-preview2-26905-02 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.0-preview3-27001-02 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview-27104-01 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview1-26907-05 [C:\Users\rybrande\.dotnet\x64\shared\Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

CC @livarcocc @mkArtakMSFT

[ryanbrandenburg]

This was solved by KnownFrameworkReference. I’ve run into a different problem, but I’ll file it as its own issue.

[ryanbrandenburg]

Can we get an issue filed against us at aspnet/AspNetCore or be otherwise notified when this kind of change is coming? It’s a real pain to find out about these things piecemeal when they start breaking us, and it can server as semi-documentation for anyone who’s doing their own templates or otherwise operating outside of the “normal” workflow (that is, aren’t using preview or RTM builds with full installers).

I’ll try that against my broken Templating branch and let you know how it turns out.