[steveisok]

Problem

The SOS Helix legs of dotnet/runtime's runtime-diagnostics pipeline are blocked. Every SOS work item fails before any test runs. This affects all runtime PRs since roughly 2026-10-23 16:00 UTC. Example: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1646832 (dotnet/runtime#136362). Each work item exits 3 with:

The Helix-provisioned runtime was not found at '<HELIX_CORRELATION_PAYLOAD>/dotnet-cli/shared/Microsoft.NETCore.App/11.0.0-rtm.26514.118'.

Root cause

For private runtime testing (PrivateBuildTesting=true + LiveRuntimeDir), src/tests/SOS.Tests/HelixPayload.targets passes --runtime-version "%(RuntimeDownload)" to runtests.sh/runtests.cmd. They use that value as the shared/Microsoft.NETCore.App/<version> folder to overlay the private runtime onto.

RuntimeDownload (MicrosoftNETCorePlatformsVersion) is the build/download version. The installed folder, however, is named after the product version (Runtime = MicrosoftNETCoreAppRefVersion). These two values were identical until #6136 moved .NET 11 to stabilized RTM versioning, so the bug went unnoticed:

	before #6136	after #6136
RuntimeDownload	11.0.0-rtm.26480.113	11.0.0-rtm.26514.118
Runtime	11.0.0-rtm.26480.113	11.0.0

How the folder gets its name: the Helix SDK's AddAdditionalRuntimes target (tools/dotnet-cli/DotNetCli.targets) resolves the archive with FindDotNetCliPackage and extracts it into dotnet-cli without changing its layout. The resolved archive, ci.dot.net/public/Runtime/11.0.0-rtm.26514.118/dotnet-runtime-11.0.0-linux-x64.tar.gz (its productVersion.txt is 11.0.0), contains shared/Microsoft.NETCore.App/11.0.0/.

Fix

• Keep downloading by RuntimeDownload (RequiredRuntimeVersions is unchanged), but pass %(HelixWorkItem.Runtime) as --runtime-version.
• Fail early with a clear error if a private runtime run has no Runtime metadata.
• Document the build-version vs. product-version distinction in the SOS.Tests README.

I checked the other places that use these versions and they need no change: the SOS harness metadata, CommonTestRunner and DbgShim already configure by Runtime, the managed Helix projects use the stable TestHostRuntimeVersion, and macOS picks --fx-version from dotnet --list-runtimes.

Validation

• I ran CreateHelixPayload through a scratch MSBuild project that imports eng/Version.Details.props, eng/Versions.props and SOS.Tests/HelixPayload.targets, with payload staging stubbed out:
  • Private, linux-x64 — before: --runtime-version "11.0.0-rtm.26514.118"; after: --runtime-version "11.0.0". RequiredRuntimeVersions stays 10.0.10;11.0.0-rtm.26514.118.
  • Private, win-x64 (runtests.cmd) — after: --runtime-version "11.0.0".
  • Non-private matrix (Net11/10/9/8) — the generated work items are unchanged.
  • Private run with empty Runtime — the new error is raised.
• I ran runtests.sh against a fake correlation payload that copies the real archive layout (shared/Microsoft.NETCore.App/11.0.0). With the old value it reproduces the exact CI error. With the new value it overlays the runtime and continues.