org.sonarsource.sonarlint.omnisharp.protocol.OmnisharpResponseP - MSBuild failed to load the project

SonarQube for IDE
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If your question is about SonarQube for IDE in the IntelliJ Platform, VS Code, Visual Studio, or Eclipse, please post it in that sub-category.

Otherwise, please provide:

  • Operating system: Windows 11
  • IDE name and flavor/env: JetBrains Rider 2026.1.2 and SonarQube for IDE (version 12.2.2.84629 SonarSource)

And a thorough description of the problem / question:

In the Log of SonarQube for IDE I see the following error:
[omnisharp-stdout-stream-consumer-17256] ERROR org.sonarsource.sonarlint.omnisharp.protocol.OmnisharpResponseProcessor - MSBuild failed to load the project

We converted our solution from .sln to .slnx project and it seems the issue is related that omnisharp doesn’t support .slnx format. See the two links:
Is .slnx support planned? · Issue #2699 · OmniSharp/omnisharp-roslyn
Add .slnx solution format support by mrt181 · Pull Request #2703 · OmniSharp/omnisharp-roslyn

I read that omnisharp will be replaced by Roslyn analyzers but haven’t found any concrete information about that.

Can you please (a) confirm that .slnx format is the root cause and (b) when a release is available which drops OmniSharp with native Roslyn-based analysis.

Best regards,
Jakob

4

Hey @Jakob, I previously implemented a workaround in our OmniSharp fork, to load .slnx solutions. It seemed to have been working for most of our users.

Would you mind sharing the full verbose logs output of SonarQube for IDE, and perhaps a small reproducer?

Could you also share which .NET version you’re using?

Thank you!