Publish MAUI Project with project reference To Class library produces errors.

Description

Publish MAUI Project with project reference To Class library produces errors.

Steps to Reproduce

1. Create Maui Project.
2. Add Class library A.
3. Add Class library B.
4. Add project reference from MAUI projects for two class librariles.
5. Publish according to this documents: https://docs.microsoft.com/en-us/dotnet/maui/windows/deployment/overview
6. I used this commands:

 New-SelfSignedCertificate -Type Custom -Subject "CN=Dani" -KeyUsage DigitalSignature -FriendlyName "My temp dev cert" -CertStoreLocation "Cert:\CurrentUser\My" -TextExtension @("2.5.29.37={text}1.3.6.1.5.5.7.3.3", "2.5.29.19={text}")
 Get-ChildItem "Cert:\CurrentUser\My" | Format-Table Subject, FriendlyName, Thumbprint
 msbuild  /restore /t:Publish /p:TargetFramework=net6.0-windows10.0.19041 /p:configuration=release /p:GenerateAppxPackageOnBuild=true /p:AppxPackageSigningEnabled=true /p:PackageCertificateThumbprint="44CF7D6F1FD0B7CF538085CBEA22A1B0ACDBB541" 

1. Get error in build phase, please see Relevant log output

Version with bug

Release Candidate 1

Last version that worked well

Release Candidate 1

Affected platforms

Windows

Affected platform versions

…

Did you find any workaround?

No

Relevant log output

"C:\Users\danis\Desktop\AutomationClient\AutomationClient.MAUI\AutomationClient.MAUI.csproj" (Restore target) (1) ->
(Restore target) ->
  C:\Users\danis\Desktop\AutomationClient\AutomationClient.MAUI\AutomationClient.MAUI.csproj : error NU1201: Project AutomationClient.Shared is not compatible with net6.0-android31.0 (.NETCoreApp,Version=v6.0). Project AutomationClient.Shared supports: net6.0-windows10.0.19041 (.NETCoreApp,Version=v6.0)
  C:\Users\danis\Desktop\AutomationClient\AutomationClient.MAUI\AutomationClient.MAUI.csproj : error NU1201: Project AutomationClient.Shared is not compatible with net6.0-ios15.4 (.NETCoreApp,Version=v6.0). Project AutomationClient.Shared supports: net6.0-windows10.0.19041 (.NETCoreApp,Version=v6.0)
  C:\Users\danis\Desktop\AutomationClient\AutomationClient.MAUI\AutomationClient.MAUI.csproj : error NU1201: Project AutomationClient.Shared is not compatible with net6.0-maccatalyst15.4 (.NETCoreApp,Version=v6.0). Project AutomationClient.Shared supports: net6.0-windows10.0.19041 (.NETCoreApp,Version=v6.0)
  C:\Users\danis\Desktop\AutomationClient\AutomationClient.MAUI\AutomationClient.MAUI.csproj : error NU1201: Project AutomationClient.Shared is not compatible with net6.0-android31.0 (.NETCoreApp,Version=v6.0) / win10-x64. Project AutomationClient.Shared supports: net6.0-windows10.0.19041 (.NETCoreApp,Version=v6.0)
  C:\Users\danis\Desktop\AutomationClient\AutomationClient.MAUI\AutomationClient.MAUI.csproj : error NU1201: Project AutomationClient.Shared is not compatible with net6.0-ios15.4 (.NETCoreApp,Version=v6.0) / win10-x64. Project AutomationClient.Shared supports: net6.0-windows10.0.19041 (.NETCoreApp,Version=v6.0)
  C:\Users\danis\Desktop\AutomationClient\AutomationClient.MAUI\AutomationClient.MAUI.csproj : error NU1201: Project AutomationClient.Shared is not compatible with net6.0-maccatalyst15.4 (.NETCoreApp,Version=v6.0) / win10-x64. Project AutomationClient.Shared supports: net6.0-windows10.0.19041 (.NETCoreApp,Version=v6.0)

    0 Warning(s)
    6 Error(s)

[Dbquity]

@mattleibow Thanks for the explanation! Now I can ditch my hefty workaround of going via nuget packages for my 10ish .NET 6 class libraries 😃

[mattleibow]

OK, so some interesting news and this feels like either a bug or a limitation of msbuild.

If you switch to dotnet build you get an error about TFMs, but this is easily fixed by adding a .0 to the end of the windows TFM:

dotnet build MauiApp1 /p:TargetFramework=net6.0-windows10.0.19041

However, for msbuild, it appears the single command of msbuild /restore throws off the part with the TFM. If you do it in 2 steps then it works:

msbuild /t:restore MauiApp1
msbuild MauiApp1 /p:TargetFramework=net6.0-windows10.0.19041.0

I think the fact that you specify a TFM during the restore somehow throws of the restore process. This can be repro-ed with just the restore target:

msbuild /t:restore MauiApp1 /p:TargetFramework=net6.0-windows10.0.19041.0

There is another workaround for this and it is probably due to the fact that the CLI arguments OVERWRITE the properties in the csproj. The workaround is to just change the singular <TargetFramework> in the class library to the plural version <TargetFrameworks>.

As a result, the CLI argument of /p:TargetFramework=net6.0-windows10.0.19041.0 no longer OVERWRITES the property but instructs the build to SELECT the best matching TFM.