Unable to run an Ooui.Xaml project from VS4Mac when XAML present

[alexeystrakh]

My Ooui.Xaml project can run and render a Xamarin.Forms page defined in code. But when I switch to a xaml file to define my UI, I'm getting the following error. If I restart the VS, it works once but then the next build fails again:

/Users/astrakh/.nuget/packages/xamarin.forms/5.0.0.2012/buildTransitive/Xamarin.Forms.targets(3,3): Error MSB4018: The "XamlCTask" task failed unexpectedly.
System.IO.IOException: Sharing violation on path /Users/astrakh/Desktop/Sources/ooui-samples/ooui-wasm/obj/Debug/net6.0/ooui-wasm.dll


Server stack trace: 
  at System.IO.FileStream..ctor (System.String path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share, System.Int32 bufferSize, System.Boolean anonymous, System.IO.FileOptions options) [0x00259] in /Users/builder/jenkins/workspace/build-package-osx-mono/2020-02/external/bockbuild/builds/mono-x64/mcs/class/corlib/System.IO/FileStream.cs:274 
  at System.IO.FileStream..ctor (System.String path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share) [0x00000] in /Users/builder/jenkins/workspace/build-package-osx-mono/2020-02/external/bockbuild/builds/mono-x64/mcs/class/corlib/System.IO/FileStream.cs:91 
  at (wrapper remoting-invoke-with-check) System.IO.FileStream..ctor(string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare)
  at Mono.Cecil.ModuleDefinition.GetFileStream (System.String fileName, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share) [0x00006] in <02cd44f94ebd4355b3be9e1dbd9d77a1>:0 
  at Mono.Cecil.ModuleDefinition.ReadModule (System.String fileName, Mono.Cecil.ReaderParameters parameters) [0x00008] in <02cd44f94ebd4355b3be9e1dbd9d77a1>:0 
  at Mono.Cecil.AssemblyDefinition.ReadAssembly (System.String fileName, Mono.Cecil.ReaderParameters parameters) [0x00000] in <02cd44f94ebd4355b3be9e1dbd9d77a1>:0 
  at Xamarin.Forms.Build.Tasks.XamlCTask.Execute (System.Collections.Generic.IList`1[System.Exception]& thrownExceptions) [0x001ba] in <61d3a1815aec4afe953f16fc8b420ef0>:0 
  at Xamarin.Forms.Build.Tasks.XamlTask.Execute () [0x00000] in <61d3a1815aec4afe953f16fc8b420ef0>:0 
  at (wrapper remoting-invoke-with-check) Xamarin.Forms.Build.Tasks.XamlTask.Execute()
  at (wrapper xdomain-dispatch) Xamarin.Forms.Build.Tasks.XamlTask.Execute(object,byte[]&,byte[]&)

Exception rethrown at [0]: 
  at (wrapper xdomain-invoke) Xamarin.Forms.Build.Tasks.XamlTask.Execute()
  at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute () [0x00023] in /Users/builder/jenkins/workspace/build-package-osx-mono-pullrequest/pr/external/bockbuild/builds/msbuild-15/src/Build/BackEnd/TaskExecutionHost/TaskExecutionHost.cs:577 
  at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask (Microsoft.Build.BackEnd.ITaskExecutionHost taskExecutionHost, Microsoft.Build.BackEnd.Logging.TaskLoggingContext taskLoggingContext, Microsoft.Build.BackEnd.TaskHost taskHost, Microsoft.Build.BackEnd.ItemBucket bucket, Microsoft.Build.BackEnd.TaskExecutionMode howToExecuteTask) [0x002b9] in /Users/builder/jenkins/workspace/build-package-osx-mono-pullrequest/pr/external/bockbuild/builds/msbuild-15/src/Build/BackEnd/Components/RequestBuilder/TaskBuilder.cs:809  (MSB4018) (ooui-wasm)

[alexeystrakh]

And if you run via dotnet CLI, another error appears (only if xaml page is present and InitializeComponent is called from the constructor):

dotnet run --project ooui-wasm.csproj
/Users/astrakh/.nuget/packages/ooui.wasm/0.14.16/build/netstandard2.0/Ooui.Wasm.targets(17,3): error : Linker failed to resolve method System.Void System.CodeDom.Compiler.GeneratedCodeAttribute::.ctor(System.String,System.String) [/Users/astrakh/Desktop/Sources/ooui-samples/ooui-wasm/ooui-wasm.csproj]
/Users/astrakh/.nuget/packages/ooui.wasm/0.14.16/build/netstandard2.0/Ooui.Wasm.targets(17,3): error : Linker failed to resolve type System.CodeDom.Compiler.GeneratedCodeAttribute in System.Runtime, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a [/Users/astrakh/Desktop/Sources/ooui-samples/ooui-wasm/ooui-wasm.csproj]

[F-Goncalves]

Same here.
Did you manage resolve this issue?

[F-Goncalves]

Nevermind. I noticed that my application was targeting .net5.0 instead of .netcore.
So I changed the TargetFramework to netcoreapp3.1 and could run it.