Running microbenchmarks fail with error NU1605

[VSadov]

Simply following instructions in https://github.com/dotnet/performance/blob/main/docs/prerequisites.md (and that used to work couple month ago)

vsadov@vsadovAMD2:~/perf/performance/src/benchmarks/micro$ ~/dotnet11/dotnet run -c Release -f net11.0 --cli ~/dotnet11/dotnet --filter 'System.Buffers.Tests.RentReturnArrayPoolTests<Byte>.ProducerConsumer' --coreRun ~/dotnet001/runtime/artifacts/bin/testhost/net11.0-linux-Release-x64/shared/Microsoft.NETCore.App/11.0.0/corerun
    /home/vsadov/perf/performance/src/benchmarks/micro/MicroBenchmarks.csproj : error NU1605:
      Warning As Error: Detected package downgrade: System.Collections.Immutable from 9.0.0 to 8.0.0. Reference the package directly from the project to select a different version.
       MicroBenchmarks -> BenchmarkDotNet.Extensions -> BenchmarkDotNet 0.16.0-nightly.20260320.467 -> Microsoft.CodeAnalysis.CSharp 5.0.0 -> System.Collections.Immutable (>= 9.0.0)
       MicroBenchmarks -> System.Collections.Immutable (>= 8.0.0-0)

This is on Linux. Not sure if Windows has the same issues.

the ~/dotnet11 contains a fairly recent SDK build copy-installed.

[LoopedBard3]

This should hopefully be fixed by #5197 which removes the old System.Collections.Immutable version, so it should not be downgraded anymore. If you want to do testing runs now, please either use the PR branch or remove <PackageReference Include="System.Collections.Immutable" Version="8.0.*-*" Condition="!$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))" /> from Microbenchmarks.csproj.

[K5BySaUdTH4K]

You might want to check your project file for any direct references to System.Collections.Immutable and update it to 9.0.0 or higher to resolve the downgrade error NU1605.

[LIxyLGy75LhmG]

Consider updating your System.Collections.Immutable package reference in your project file to 9.0.0 or higher to avoid the NU1605 error you’re encountering, as the downgrade issue is likely due to the conflicting version requirements from BenchmarkDotNet.