Unity Bug Repro

Missing Dataflow dll 4.0.0.0

Unity Version: broken with 2021.2.12 up to 2021.3.2, works with 2021.2.0 up to 2021.2.11

What should happen: Android build completes successfully

What happens: Android build fails

Triggered by

We manually add the dll for System.Threading.Tasks.Dataflow in version 5.0.0 and build for Android IL2CPP, compatibility set to .Net Framework. The build fails with this error:

Building Library\Bee\artifacts\Android\ManagedStripped failed with output:
C:\Program Files\Unity\Hub\Editor\2021.3.2f1\Editor\Data\il2cpp\build\deploy\UnityLinker.exe --search-directory=C:/work/reprobug/dataflow/Dataflow/Temp/StagingArea/Data/Managed --out=Library/Bee/artifacts/Android/ManagedStripped --include-link-xml=C:/work/reprobug/dataflow/Dataflow/Temp/StagingArea/Data/Managed\TypesInScenes.xml --include-link-xml=C:/Program Files/Unity/Hub/Editor/2021.3.2f1/Editor/Data/PlaybackEngines/AndroidPlayer/Tools/AndroidNativeLink.xml --include-directory=C:/work/reprobug/dataflow/Dataflow/Temp/StagingArea/Data/Managed --dotnetprofile=unityaot-linux --dotnetruntime=Il2Cpp --platform=Android --use-editor-options --enable-engine-module-stripping --engine-modules-asset-file=C:/Program Files/Unity/Hub/Editor/2021.3.2f1/Editor/Data/PlaybackEngines/AndroidPlayer/modules.asset --editor-data-file=C:/work/reprobug/dataflow/Dataflow/Temp/StagingArea/Data/Managed/EditorToUnityLinkerData.json --include-unity-root-assembly=C:/work/reprobug/dataflow/Dataflow/Temp/StagingArea/Data/Managed/Assembly-CSharp.dll --print-command-line
Fatal error in Unity CIL Linker
Mono.Cecil.AssemblyResolutionException: Failed to resolve assembly: 'System.Threading.Tasks.Dataflow, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null'
   at Unity.IL2CPP.Common.MissingMethodStubber.GetTypeModule(TypeReference type, IEnumerable`1 assemblies)
   at Unity.Linker.Steps.AddUnresolvedStubsStep.MarkAssemblyOfType(UnityLinkContext context, TypeReference type)
   at Unity.Linker.Steps.Marking.UnresolvedStubMarking.HandleUnresolvedType(TypeReference reference)
   at Unity.Linker.Steps.UnityMarkStep.HandleUnresolvedType(TypeReference reference)
   at Mono.Linker.Steps.MarkStep.MarkType(TypeReference reference, DependencyInfo reason, IMemberDefinition sourceLocationMember)
   at Mono.Linker.Steps.MarkStep.MarkField(FieldDefinition field, DependencyInfo& reason)
   at Mono.Linker.Steps.MarkStep.MarkEntireTypeInternal(TypeDefinition type, Boolean includeBaseTypes, DependencyInfo& reason, IMemberDefinition sourceLocationMember, HashSet`1 typesAlreadyVisited)
   at Mono.Linker.Steps.MarkStep.MarkEntireAssembly(AssemblyDefinition assembly)
   at Mono.Linker.Steps.MarkStep.InitializeAssembly(AssemblyDefinition assembly)
   at Unity.Linker.Steps.UnityMarkStep.InitializeAssembly(AssemblyDefinition assembly)
   at Mono.Linker.Steps.MarkStep.Initialize()
   at Mono.Linker.Steps.MarkStep.Process(LinkContext context)
   at Unity.Linker.Steps.UnityMarkStep.Process(LinkContext context)
   at Unity.Linker.UnityPipeline.ProcessStep(LinkContext context, IStep step)
   at Mono.Linker.Pipeline.Process(LinkContext context)
   at Unity.Linker.UnityDriver.UnityRun(Boolean noProfilerAllowed, ILogger customLogger)
   at Unity.Linker.UnityDriver.RunDriverWithoutErrorHandling(ILogger customLogger, Boolean noProfilerAllowed)
   at Unity.Linker.UnityDriver.RunDriver()
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)

This is the important part:

Fatal error in Unity CIL Linker
Mono.Cecil.AssemblyResolutionException: Failed to resolve assembly: 'System.Threading.Tasks.Dataflow, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null'

This happens even if we set the dll to be excluded from Android.