Android .NET 6 Preview 5 fallbacks not working

[jonathanpeppers]

Details about Problem

NuGet product used: dotnet.exe

Product version: .NET 6.0.100-preview.6.21276.2 or .NET 6.0.100-preview.5.21278.1

Worked before? If so, with which NuGet version: this was testing a new feature in NuGet

Repro steps and/or sample project

Context: https://github.com/dotnet/designs/blob/main/accepted/2021/net6.0-tfms/net6.0-tfms.md
Context: NuGet/NuGet.Client#4042
Context: dotnet/android#5973

We had some workarounds for NuGet since early in .NET 5 development. This involved setting $(AssetTargetFallback) and/or $(PackageTargetFallback).

We got on a build of dotnet/installer that includes: #10819

So I removed our workarounds, however I hit an error during restore on this sample app:

https://github.com/dotnet/maui-samples/tree/main/HelloAndroid

HelloAndroid.csproj : error NU1202: Package Xamarin.AndroidX.Migration 1.0.8 is not compatible with net6.0-android30.0 (.NETCoreApp,Version=v6.0). Package Xamarin.AndroidX.Migration 1.0.8 supports: monoandroid90 (MonoAndroid,Version=v9.0)

It seems like this restore should succeed? This package only has monoandroid90 inside. Thanks!

Verbose Logs

msbuild.zip

[jonathanpeppers]

/cc @zkat

[jonathanpeppers]

Actually, perhaps we don't have a new enough dotnet/installer:

https://github.com/dotnet/installer/blob/3ebe0ca9715283842b003a75cf2b3603ca28d964/eng/Version.Details.xml#L124-L127

I'll try using a newer build.

[heng-liu]

I think you're right. The PR related to NuGet is inserted into dotnet release/6.0.1xx-preview5 branch not long ago.

[heng-liu]

I'll close the issue for now. Please reopen it if the new build still doesn't work. Thanks!