ResolvePackageFileConflicts is emitting confusing conflict messages when building .NET 3.5 projects.

Steps to Reproduce

1. Setup environment with msbuild 15.5 or newer
2. Create a new .NET 3.5 project
3. Build - msbuild /t:build

Actual Results The build output indicates there are a bunch of package conflicts

...
Using "ResolvePackageFileConflicts" task from assembly "C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\\tools\net46\Microsoft.NET.Build.Extensions.Tasks.dll".
Task "ResolvePackageFileConflicts"
  Encountered conflict between 'Platform:System.DirectoryServices.AccountManagement.dll' and 'Platform:System.DirectoryServices.AccountManagement.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Net.dll' and 'Platform:System.Net.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.ComponentModel.DataAnnotations.dll' and 'Platform:System.ComponentModel.DataAnnotations.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Abstractions.dll' and 'Platform:System.Web.Abstractions.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Routing.dll' and 'Platform:System.Web.Routing.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.DynamicData.dll' and 'Platform:System.Web.DynamicData.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.DynamicData.Design.dll' and 'Platform:System.Web.DynamicData.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Extensions.Design.dll' and 'Platform:System.Web.Extensions.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Extensions.dll' and 'Platform:System.Web.Extensions.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Core.dll' and 'Platform:System.Core.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Conversion.v3.5.dll' and 'Platform:Microsoft.Build.Conversion.v3.5.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Utilities.v3.5.dll' and 'Platform:Microsoft.Build.Utilities.v3.5.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Tasks.v3.5.dll' and 'Platform:Microsoft.Build.Tasks.v3.5.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Engine.dll' and 'Platform:Microsoft.Build.Engine.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Framework.dll' and 'Platform:Microsoft.Build.Framework.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.DataSetExtensions.dll' and 'Platform:System.Data.DataSetExtensions.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.AddIn.dll' and 'Platform:System.AddIn.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.AddIn.Contract.dll' and 'Platform:System.AddIn.Contract.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Linq.dll' and 'Platform:System.Data.Linq.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Xml.Linq.dll' and 'Platform:System.Xml.Linq.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Management.Instrumentation.dll' and 'Platform:System.Management.Instrumentation.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.ServiceModel.Web.dll' and 'Platform:System.ServiceModel.Web.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.WorkflowServices.dll' and 'Platform:System.WorkflowServices.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.VisualC.STLCLR.dll' and 'Platform:Microsoft.VisualC.STLCLR.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.VisualC.STLCLR.dll' and 'Platform:Microsoft.VisualC.STLCLR.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Windows.Presentation.dll' and 'Platform:System.Windows.Presentation.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Sentinel.v3.5Client.dll' and 'Platform:Sentinel.v3.5Client.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Entity.dll' and 'Platform:System.Data.Entity.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Entity.Design.dll' and 'Platform:System.Data.Entity.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Entity.dll' and 'Platform:System.Web.Entity.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Entity.Design.dll' and 'Platform:System.Web.Entity.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Services.dll' and 'Platform:System.Data.Services.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Services.Client.dll' and 'Platform:System.Data.Services.Client.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Services.Design.dll' and 'Platform:System.Data.Services.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Engine.dll' and 'Platform:Microsoft.Build.Engine.dll'.  Choosing 'Platform:Microsoft.Build.Engine.dll' because AssemblyVersion '3.5.0.0' is greater than '2.0.0.0'.
  Encountered conflict between 'Platform:Microsoft.Build.Framework.dll' and 'Platform:Microsoft.Build.Framework.dll'.  Choosing 'Platform:Microsoft.Build.Framework.dll' because AssemblyVersion '3.5.0.0' is greater than '2.0.0.0'.
  Encountered conflict between 'Platform:MSBuild.dll' and 'Platform:MSBuild.dll'.  Choosing 'Platform:MSBuild.dll' because AssemblyVersion '3.5.0.0' is greater than '2.0.0.0'.
  Encountered conflict between 'Platform:System.DirectoryServices.AccountManagement.dll' and 'Platform:System.DirectoryServices.AccountManagement.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Net.dll' and 'Platform:System.Net.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.ComponentModel.DataAnnotations.dll' and 'Platform:System.ComponentModel.DataAnnotations.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Abstractions.dll' and 'Platform:System.Web.Abstractions.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Routing.dll' and 'Platform:System.Web.Routing.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.DynamicData.dll' and 'Platform:System.Web.DynamicData.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.DynamicData.Design.dll' and 'Platform:System.Web.DynamicData.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Extensions.Design.dll' and 'Platform:System.Web.Extensions.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Extensions.dll' and 'Platform:System.Web.Extensions.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Core.dll' and 'Platform:System.Core.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Conversion.v3.5.dll' and 'Platform:Microsoft.Build.Conversion.v3.5.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Utilities.v3.5.dll' and 'Platform:Microsoft.Build.Utilities.v3.5.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Tasks.v3.5.dll' and 'Platform:Microsoft.Build.Tasks.v3.5.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Engine.dll' and 'Platform:Microsoft.Build.Engine.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Framework.dll' and 'Platform:Microsoft.Build.Framework.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.DataSetExtensions.dll' and 'Platform:System.Data.DataSetExtensions.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.AddIn.dll' and 'Platform:System.AddIn.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.AddIn.Contract.dll' and 'Platform:System.AddIn.Contract.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Linq.dll' and 'Platform:System.Data.Linq.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Xml.Linq.dll' and 'Platform:System.Xml.Linq.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Management.Instrumentation.dll' and 'Platform:System.Management.Instrumentation.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.ServiceModel.Web.dll' and 'Platform:System.ServiceModel.Web.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.WorkflowServices.dll' and 'Platform:System.WorkflowServices.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.VisualC.STLCLR.dll' and 'Platform:Microsoft.VisualC.STLCLR.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.VisualC.STLCLR.dll' and 'Platform:Microsoft.VisualC.STLCLR.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Windows.Presentation.dll' and 'Platform:System.Windows.Presentation.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Sentinel.v3.5Client.dll' and 'Platform:Sentinel.v3.5Client.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Entity.dll' and 'Platform:System.Data.Entity.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Entity.Design.dll' and 'Platform:System.Data.Entity.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Entity.dll' and 'Platform:System.Web.Entity.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Web.Entity.Design.dll' and 'Platform:System.Web.Entity.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Services.dll' and 'Platform:System.Data.Services.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Services.Client.dll' and 'Platform:System.Data.Services.Client.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:System.Data.Services.Design.dll' and 'Platform:System.Data.Services.Design.dll'.  Could not determine winner due to equal file and assembly versions.
  Encountered conflict between 'Platform:Microsoft.Build.Engine.dll' and 'Platform:Microsoft.Build.Engine.dll'.  Choosing 'Platform:Microsoft.Build.Engine.dll' because AssemblyVersion '3.5.0.0' is greater than '2.0.0.0'.
  Encountered conflict between 'Platform:Microsoft.Build.Framework.dll' and 'Platform:Microsoft.Build.Framework.dll'.  Choosing 'Platform:Microsoft.Build.Framework.dll' because AssemblyVersion '3.5.0.0' is greater than '2.0.0.0'.
  Encountered conflict between 'Platform:MSBuild.dll' and 'Platform:MSBuild.dll'.  Choosing 'Platform:MSBuild.dll' because AssemblyVersion '3.5.0.0' is greater than '2.0.0.0'.
Done executing task "ResolvePackageFileConflicts".
...

Expected Results

1. The conflict message itself it confusing. The message doesn’t indicate what the source of the two “platform” conflicts are. I wouldn’t expect the platform to have conflicts within itself.
2. The conflict messages are the majority of the output. I would expect that the build output of a new empty project with the default verbosity would be pretty simple and understandable.

Notes of Interest:

1. This appears to be a behavior change introduced in 15.5. The 15.4 output does not include these conflicts.
2. The diagnostic output indicates the following TargetFrameworkDirectories are detected

  Task Parameter:
      TargetFrameworkDirectories=
          C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.5\
          C:\Windows\Microsoft.NET\Framework\v3.5\
          "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.0\"
          C:\Windows\Microsoft.NET\Framework\v3.0\
          C:\Windows\Microsoft.NET\Framework\v2.0.50727\ (TaskId:8)

1. The C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.5\RedistList\FrameworkList.xml includes multiple entries for most assemblies.

...
  <File AssemblyName="System.Core" Version="3.5.0.0" PublicKeyToken="b77a5c561934e089" Culture="neutral" ProcessorArchitecture="MSIL" InGAC="false" />
  <File AssemblyName="System.Core" Version="3.5.0.0" PublicKeyToken="b77a5c561934e089" Culture="neutral" ProcessorArchitecture="MSIL" InGAC="true" />
...

[JoachimRaue-EH]

Any news on this? The bug is open for almost two years… I am also struggling with megabytes worth of useless log entries.

[rschindhelm-haba]

We’ve encountered this on our TFS 2018 CI builds when building a .NET Framework application which uses .NET Standard libraries, using the Visual Studio Build task (MSBuild).

Excerpt:

2019-03-06T07:11:21.1661481Z _HandlePackageFileConflicts:
2019-03-06T07:11:21.1661481Z C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\Microsoft.NET.Build.Extensions.ConflictResolution.targets(33,5): message NETSDK1041: Encountered conflict between 'Reference:System.Runtime.InteropServices.RuntimeInformation, Version=4.0.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL' and 'Reference:System.Runtime.InteropServices.RuntimeInformation'.  NETSDK1033: Choosing 'Reference:System.Runtime.InteropServices.RuntimeInformation' because AssemblyVersion '4.0.2.0' is greater than '4.0.1.0'. [c:\agent\_work\8\s\src\SampleProject\src\DotNetFullFrameworkApplication.csproj]
2019-03-06T07:11:21.1661481Z C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\Microsoft.NET.Build.Extensions.ConflictResolution.targets(33,5): message NETSDK1041: Encountered conflict between 'Reference:System.IO.Compression.ZipFile, Version=4.0.2.0, Culture=neutral, PublicKeyToken=b77a5c561934e089, processorArchitecture=MSIL' and 'Reference:System.IO.Compression.ZipFile'.  NETSDK1033: Choosing 'Reference:System.IO.Compression.ZipFile' because AssemblyVersion '4.0.3.0' is greater than '4.0.2.0'. [c:\agent\_work\8\s\src\SampleProject\src\DotNetFullFrameworkApplication.csproj]
2019-03-06T07:11:21.1974031Z C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\Microsoft.NET.Build.Extensions.ConflictResolution.targets(33,5): message NETSDK1041: Encountered conflict between 'Reference:Microsoft.Build.Framework, Version=15.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL' and 'Platform:Microsoft.Build.Framework.dll'.  NETSDK1033: Choosing 'Reference:Microsoft.Build.Framework, Version=15.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL' because AssemblyVersion '15.1.0.0' is greater than '4.0.0.0'. [c:\agent\_work\8\s\src\SampleProject\src\DotNetFullFrameworkApplication.csproj]
2019-03-06T07:11:21.1974031Z C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\Microsoft.NET.Build.Extensions.ConflictResolution.targets(33,5): message NETSDK1041: Encountered conflict between 'Reference:System.IO.Compression' and 'Platform:System.IO.Compression.dll'.  NETSDK1033: Choosing 'Reference:System.IO.Compression' because AssemblyVersion '4.2.0.0' is greater than '4.0.0.0'. [c:\agent\_work\8\s\src\SampleProject\src\DotNetFullFrameworkApplication.csproj]
2019-03-06T07:11:21.1974031Z C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\Microsoft.NET.Build.Extensions.ConflictResolution.targets(33,5): message NETSDK1041: Encountered conflict between 'Reference:System.Net.Http' and 'Platform:System.Net.Http.dll'.  NETSDK1033: Choosing 'Reference:System.Net.Http' because AssemblyVersion '4.2.0.0' is greater than '4.0.0.0'. [c:\agent\_work\8\s\src\SampleProject\src\DotNetFullFrameworkApplication.csproj]
2019-03-06T07:11:21.1974031Z C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\Microsoft.NET.Build.Extensions.ConflictResolution.targets(33,5): message NETSDK1041: Encountered conflict between 'Reference:System.Collections' and 'Platform:System.Collections.dll'.  NETSDK1033: Choosing 'Reference:System.Collections' because AssemblyVersion '4.0.11.0' is greater than '4.0.10.0'. [c:\agent\_work\8\s\src\SampleProject\src\DotNetFullFrameworkApplication.csproj]