Unexpected NU1605 from transitive reference that was never selected (pruned subgraph)

[madelson]

Details about Problem

NuGet product used (NuGet.exe | Visual Studio | MSBuild.exe | dotnet.exe): NuGet CLI 5.9.1, VS 16.10.2

Repro steps and/or sample project

Using the provided solution:

ReproUnexpectedNU1605.zip

• Build projects ReproPackageCV1 and ReproPackageCV2 -> copy .nupkgs to local feed
• Build projects ReproPackageA and ReproPackageB -> copy .nupkgs to local feed
• Run nuget restore -ForceEvaluate ReproUnexpectedNU1605.sln -> fails with

Errors in C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\Repro.csproj
NU1605: Detected package downgrade: System.Memory from 4.5.4 to 4.5.2. Reference the package directly from the project to select a different version.
Repro -> ReproPackageA 1.0.0 -> ReproPackageC 1.0.0 -> Microsoft.Extensions.Configuration 5.0.0 -> Microsoft.Extensions.Primitives 5.0.0 -> System.Memory (>= 4.5.4)
Repro -> System.Memory (>= 4.5.2)

High level description

• In this project we reference 2 packages A and B as well as System.Memory 4.5.2.
• A references C >= 1.0 and B references C >= 1.1.
• C 1.0 references Microsoft.Extensions.Configuration 5.0 which ultimately requires System.Memory 4.5.4
• C 1.1 references Microsoft.Extensions.Configuration 3.11.1 which ultimately requires System.Memory 4.5.2

When restoring, as you'd expect it NuGet resolves C 1.1. HOWEVER, it then complains that the direct reference to System.Memory 4.5.2 is incompatible with the chain of references coming from C 1.0. This feels like a bug to me (but also maybe I'm misunderstanding some nuance of the restore logic?).

Verbose Logs

$ nuget restore -verbosity detailed -forceevaluate ReproUnexpectedNU1605.sln && echo success
NuGet Version: 5.9.1.11
MSBuild auto-detection: using msbuild version '16.10.2.30804' from 'C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\bin'. Use option -MSBuildVersion to force nuget to use a specific version of MSBuild.
MSBuild P2P timeout [ms]: 120000
C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\bin\msbuild.exe "C:\Users\madelson\AppData\Local\Temp\NuGetScratch\yk0lrx2b.tff.nugetinputs.targets" /t:GenerateRestoreGraphFile /nologo /nr:false /v:q /p:NuGetRestoreTargets="C:\Users\madelson\AppData\Local\Temp\NuGetScratch\4hpulsil.cl4.nugetrestore.targets" /p:RestoreUseCustomAfterTargets="True" /p:RestoreTaskAssemblyFile="C:\NuGet\NuGet.exe" /p:RestoreSolutionDirectory="C:\users\madelson\source\repos\ReproUnexpectedNU1605\" /p:SolutionDir="C:\users\madelson\source\repos\ReproUnexpectedNU1605\" /p:SolutionName="ReproUnexpectedNU1605"

Running restore with 16 concurrent jobs.
Reading project file C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1_1\ReproPackageCV1_1.csproj.
Reading project file C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageA\ReproPackageA.csproj.
Reading project file C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageB\ReproPackageB.csproj.
Reading project file C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\Repro.csproj.
Reading project file C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1\ReproPackageCV1.csproj.
Restoring packages for C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\Repro.csproj...
Restoring packages for C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1\ReproPackageCV1.csproj...
Restoring packages for C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageA\ReproPackageA.csproj...
Restoring packages for C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1_1\ReproPackageCV1_1.csproj...
Restoring packages for C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageB\ReproPackageB.csproj...
Restoring packages for .NETStandard,Version=v2.0...
Restoring packages for .NETStandard,Version=v2.0...
Restoring packages for .NETStandard,Version=v2.0...
Restoring packages for .NETStandard,Version=v2.0...
Restoring packages for .NETStandard,Version=v2.0...
Resolving conflicts for .NETStandard,Version=v2.0...
Resolving conflicts for .NETStandard,Version=v2.0...
Resolving conflicts for .NETStandard,Version=v2.0...
Resolving conflicts for .NETStandard,Version=v2.0...
Resolving conflicts for .NETStandard,Version=v2.0...
Checking compatibility of packages on .NETStandard,Version=v2.0.
Checking compatibility of packages on .NETStandard,Version=v2.0.
Checking compatibility of packages on .NETStandard,Version=v2.0.
Checking compatibility of packages on .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageA 1.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for NETStandard.Library 2.0.3 with .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageB 1.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for NETStandard.Library 2.0.3 with .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageC 1.1.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageC 1.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration 5.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageC 1.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.NETCore.Platforms 1.1.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration 5.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration.Abstractions 5.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Primitives 5.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Buffers 4.5.1 with .NETStandard,Version=v2.0.
Checking compatibility for System.Memory 4.5.4 with .NETStandard,Version=v2.0.
Checking compatibility for System.Runtime.CompilerServices.Unsafe 5.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Numerics.Vectors 4.4.0 with .NETStandard,Version=v2.0.
All packages and projects are compatible with .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageC 1.1.0 with .NETStandard,Version=v2.0.
Checking compatibility for NETStandard.Library 2.0.3 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration.Abstractions 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.NETCore.Platforms 1.1.0 with .NETStandard,Version=v2.0.
Checking compatibility for NETStandard.Library 2.0.3 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration.Abstractions 5.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration.Abstractions 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Primitives 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.NETCore.Platforms 1.1.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Primitives 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for System.Memory 4.5.2 with .NETStandard,Version=v2.0.
Checking compatibility for System.Runtime.CompilerServices.Unsafe 4.7.1 with .NETStandard,Version=v2.0.
Checking compatibility for System.Buffers 4.4.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Numerics.Vectors 4.4.0 with .NETStandard,Version=v2.0.
All packages and projects are compatible with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Primitives 5.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.NETCore.Platforms 1.1.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Buffers 4.5.1 with .NETStandard,Version=v2.0.
Checking compatibility for System.Memory 4.5.4 with .NETStandard,Version=v2.0.
Checking compatibility for System.Runtime.CompilerServices.Unsafe 5.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Numerics.Vectors 4.4.0 with .NETStandard,Version=v2.0.
All packages and projects are compatible with .NETStandard,Version=v2.0.
Checking compatibility for System.Memory 4.5.2 with .NETStandard,Version=v2.0.
Checking compatibility for System.Runtime.CompilerServices.Unsafe 4.7.1 with .NETStandard,Version=v2.0.
Checking compatibility for System.Buffers 4.4.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Numerics.Vectors 4.4.0 with .NETStandard,Version=v2.0.
All packages and projects are compatible with .NETStandard,Version=v2.0.
NU1605: Detected package downgrade: System.Memory from 4.5.4 to 4.5.2. Reference the package directly from the project to select a different version.
Repro -> ReproPackageA 1.0.0 -> ReproPackageC 1.0.0 -> Microsoft.Extensions.Configuration 5.0.0 -> Microsoft.Extensions.Primitives 5.0.0 -> System.Memory (>= 4.5.4)
Repro -> System.Memory (>= 4.5.2)
Checking compatibility of packages on .NETStandard,Version=v2.0.
Checking compatibility for Repro 1.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for NETStandard.Library 2.0.3 with .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageA 1.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageB 1.0.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Memory 4.5.2 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.NETCore.Platforms 1.1.0 with .NETStandard,Version=v2.0.
Checking compatibility for ReproPackageC 1.1.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Buffers 4.4.0 with .NETStandard,Version=v2.0.
Checking compatibility for System.Numerics.Vectors 4.4.0 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Configuration.Abstractions 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for Microsoft.Extensions.Primitives 3.1.11 with .NETStandard,Version=v2.0.
Checking compatibility for System.Runtime.CompilerServices.Unsafe 4.7.1 with .NETStandard,Version=v2.0.
All packages and projects are compatible with .NETStandard,Version=v2.0.
Committing restore...
Committing restore...
Committing restore...
Committing restore...
Committing restore...
Generating MSBuild file C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageB\obj\ReproPackageB.csproj.nuget.g.props.
Generating MSBuild file C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\obj\Repro.csproj.nuget.g.props.
Generating MSBuild file C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1_1\obj\ReproPackageCV1_1.csproj.nuget.g.props.
Generating MSBuild file C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1\obj\ReproPackageCV1.csproj.nuget.g.props.
Generating MSBuild file C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageA\obj\ReproPackageA.csproj.nuget.g.props.
Assets file has not changed. Skipping assets file writing. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1\obj\project.assets.json
Assets file has not changed. Skipping assets file writing. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageB\obj\project.assets.json
Assets file has not changed. Skipping assets file writing. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1_1\obj\project.assets.json
Assets file has not changed. Skipping assets file writing. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageA\obj\project.assets.json
Writing cache file to disk. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1\obj\project.nuget.cache
Writing cache file to disk. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageB\obj\project.nuget.cache
Writing cache file to disk. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1_1\obj\project.nuget.cache
Writing cache file to disk. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageA\obj\project.nuget.cache
Writing assets file to disk. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\obj\project.assets.json
Persisting dg to C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1_1\obj\ReproPackageCV1_1.csproj.nuget.dgspec.json
Persisting dg to C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageA\obj\ReproPackageA.csproj.nuget.dgspec.json
Persisting dg to C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageB\obj\ReproPackageB.csproj.nuget.dgspec.json
Persisting dg to C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1\obj\ReproPackageCV1.csproj.nuget.dgspec.json
Restored C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1\ReproPackageCV1.csproj (in 501 ms).
Restored C:\users\madelson\source\repos\ReproUnexpectedNU1605\ReferencedV1_1\ReproPackageCV1_1.csproj (in 501 ms).
Restored C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageB\ReproPackageB.csproj (in 501 ms).
Restored C:\users\madelson\source\repos\ReproUnexpectedNU1605\PackageA\ReproPackageA.csproj (in 504 ms).
Writing cache file to disk. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\obj\project.nuget.cache
Writing packages lock file at disk. Path: C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\packages.lock.json
Persisting dg to C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\obj\Repro.csproj.nuget.dgspec.json
Failed to restore C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\Repro.csproj (in 502 ms).

Errors in C:\users\madelson\source\repos\ReproUnexpectedNU1605\Repro\Repro.csproj
NU1605: Detected package downgrade: System.Memory from 4.5.4 to 4.5.2. Reference the package directly from the project to select a different version.
Repro -> ReproPackageA 1.0.0 -> ReproPackageC 1.0.0 -> Microsoft.Extensions.Configuration 5.0.0 -> Microsoft.Extensions.Primitives 5.0.0 -> System.Memory (>= 4.5.4)
Repro -> System.Memory (>= 4.5.2)

NuGet Config files used:
C:\Users\madelson\AppData\Roaming\NuGet\NuGet.Config
C:\Program Files (x86)\NuGet\Config\Microsoft.VisualStudio.Offline.config

Feeds used:
C:\LocalNugetRepo
https://www.nuget.org/api/v2/

[nkolev92]

Thanks for the great repro!

This looks like a bug, as the error is not very helpful because the subgraph has been pruned.

I tweaked your repro a bit to allow it to be runnable with a single script, https://github.com/nkolev92/NU1605ReportedForPrunedSubgraph-10972.

[madelson]

@nkolev92 great to see movement here; do you know which NuGet client release would have the fix?

[nkolev92]

The fix would be in 6.0, both NuGet 6.0 and .NET SDK 6.0.1xx

[madelson]

Great! Any chance of a prerelease package on NuGet.org before then?

[nkolev92]

The restore build tasks can't really ship as a package, but there are a few other ways to dogfood:

• NuGet.exe previews.
• dotnet.exe nightlies (dotnet.exe public previews)
• Visual Studio previews