[BUILD] Build Failure .NET Core 2.1.0 missing

[michael-hawker]

Describe the bug

Our build pipeline is failing. FYI @azchohfi @Arlodotexe @Sergio0694... 😢

Think this may have to do with .NET Core 2.x retiring?

See failure from other PR here: https://dev.azure.com/dotnet/CommunityToolkit/_build/results?buildId=66861&view=logs&j=4a47a688-b50e-58f6-4d2c-6d1b829fc8e2&t=ae438b9a-8c74-5e36-ef90-6b85cacfd6fb&l=1800 (I had built this commit locally with our build script and it worked fine.)

Running NetCore Unit Tests
Build started 3/5/2022 1:05:03 AM.
Test run for D:\a\1\s\UnitTests\UnitTests.Notifications.NetCore\bin\Release\netcoreapp2.1\UnitTests.Notifications.NetCore.dll (.NETCoreApp,Version=v2.1)
Microsoft (R) Test Execution Command Line Tool Version 16.11.0
Copyright (c) Microsoft Corporation.  All rights reserved.

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
Testhost process exited with error: It was not possible to find any compatible framework version
The framework 'Microsoft.NETCore.App', version '2.1.0' was not found.
  - The following frameworks were found:
      3.1.4 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
      3.1.6 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
      3.1.20 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
      3.1.22 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
      5.0.4 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
      5.0.9 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
      5.0.14 at [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
You can resolve the problem by installing the specified framework and/or SDK.
The specified framework can be found at:
  - https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=2.1.0&arch=x64&rid=win10-x64
. Please check the diagnostic logs for more information.

Anyone remember where this is configured?

Regression

No response

Reproducible in sample app?

• This bug can be reproduced in the sample app.

Steps to reproduce

Kick off a Build in the CI

Expected behavior

Build should pass.

Screenshots

No response

Windows Build Number

• Windows 10 1809 (Build 17763)
• Windows 10 1903 (Build 18362)
• Windows 10 1909 (Build 18363)
• Windows 10 2004 (Build 19041)
• Windows 10 20H2 (Build 19042)
• Windows 10 21H1 (Build 19043)
• Windows 11 21H2 (Build 22000)
• Other (specify)

Other Windows Build number

No response

App minimum and target SDK version

• Windows 10, version 1809 (Build 17763)
• Windows 10, version 1903 (Build 18362)
• Windows 10, version 1909 (Build 18363)
• Windows 10, version 2004 (Build 19041)
• Other (specify)

Other SDK version

No response

Visual Studio Version

No response

Visual Studio Build Number

No response

Device form factor

No response

Nuget packages

No response

Additional context

No response

Help us help you

Yes, but only if others can assist.

[Sergio0694]

Mmh this might just be a leftover we forgot to nuke. All .NET Code 2.1 targets should just be deleted, yeah. I can help with a PR if you need 🙂

[michael-hawker]

Thanks @Sergio0694 that'd be great if you could take a quick look on Monday. 🦙❤