Can't build on VS 2019 16.8

[vgromfeld]

Describe the bug

After updating VS2019 to 16.8, the Windows Community Toolkit solution is no longer building.

The build is failing at the nuget restoration step with:

1>------ Rebuild All started: Project: Microsoft.Toolkit, Configuration: Debug Any CPU ------
Error occurred while restoring NuGet packages: Invalid restore input. Duplicate frameworks found: 'netstandard1.4, uap10.0.17763, uap10.0.17763, net461, netcoreapp3.1'. Input files: C:\[...]\WindowsCommunityToolkit\Microsoft.Toolkit.Uwp.Notifications\Microsoft.Toolkit.Uwp.Notifications.csproj.
1>Microsoft.Toolkit -> C:\[...]\WindowsCommunityToolkit\Microsoft.Toolkit\bin\Debug\netstandard2.1\Microsoft.Toolkit.dll
1>Microsoft.Toolkit -> C:\[...]\WindowsCommunityToolkit\Microsoft.Toolkit\bin\Debug\netstandard1.4\Microsoft.Toolkit.dll
1>Microsoft.Toolkit -> C:\[...]\WindowsCommunityToolkit\Microsoft.Toolkit\bin\Debug\netstandard2.0\Microsoft.Toolkit.dll
========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========

• Is this bug a regression in the toolkit? If so, what toolkit version did you last see it work:

Steps to Reproduce

• Can this be reproduced in the Sample App? (Either in a sample as-is or with new XAML pasted in the editor.) If so, please provide custom XAML or steps to reproduce. If not, let us know why it can't be reproduced (e.g. more complex setup, environment, dependencies, etc...)

Steps to reproduce the behavior:

1. Update VS2019 to 18.8.1
2. Open the solution
3. Build or rebuild solution

Expected behavior

The solution builds.

Environment

NuGet Package(s): 

Package Version(s): 

Windows 10 Build Number:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [X] May 2020 Update (19041)
- [ ] Insider Build (build number: )

Visual Studio 
- [ ] 2017 (version: )
- [X] 2019 (version: 16.8.1) 
- [ ] 2019 Preview (version: )

Additional context

The problem seems to be related to the Microsoft.Toolkit.Uwp.Notifications.csproj

Removing the native target from the TargetFrameworks list of the project fix the nuget restore operation but then the build is failing later with symbols not being found.

I changed
<TargetFrameworks>netstandard1.4;uap10.0;native;net461;netcoreapp3.1</TargetFrameworks>
to
<TargetFrameworks>netstandard1.4;uap10.0;net461;netcoreapp3.1</TargetFrameworks>

Hello vgromfeld, thank you for opening an issue with us!

I have automatically added a "needs triage" label to help get things started. Our team will analyze and investigate the issue, and escalate it to the relevant team if possible. Other community members may also look into the issue and provide feedback 🙌

[Kyaa-dost]

@vgromfeld Correct as you mentioned currently removing the 'native' in Microsoft.Toolkit.Uwp.Notifications.csproj should do the job. Hopefully, this will get fixed soon 🚀

[davesmits]

Not sure if understand you; how do i remove it? I just included with the nuget so dont have the csproject

[vgromfeld]

@davesmits, I faced the issue while working on a PR for the toolkit. I had the UWP Community Toolkit solution opened.
Unfortunately, if you're just consuming the nuget package, this workaround does not apply to you 😥

[michael-hawker]

@vgromfeld we filed an issue with the VS team on this and are awaiting more info: https://developercommunity.visualstudio.com/content/problem/1249858/failing-to-build-project-with-vs168.html

@davesmits interesting to know this is happening when consuming the NuGet as well, can you provide some more details on that? (Ah, see you filed #3565, think that's an independent issue.)