[ci-scan] Build break: crossgen2 fails to load Microsoft.CodeAnalysis compiling Compliance.Tests #132052

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1545314
Build error leg or test failing: linux-x64 / windows-x64 / osx-x64 Release TestReadyToRun_Libraries — Build product (Compliance.Tests crossgen)

Pipeline: runtime-coreclr crossgen2 (definition 124), branch main. The Build product step fails on all three test-build legs (linux-x64, windows-x64, osx-x64) while crossgen-compiling Compliance.Tests, so Send to Helix is skipped. The break persists into follow-up build 1545712.

Error Details

Crossgen (via Microsoft.NET.CrossGen.targets) fails to load Microsoft.CodeAnalysis while ahead-of-time compiling src/libraries/Common/tests/ComplianceTests/Compliance.Tests.csproj, throwing a TypeSystemException.FileNotFoundException from the crossgen2 type system.

Microsoft.NET.CrossGen.targets(501,5): error : Error: Failed to load assembly 'Microsoft.CodeAnalysis'
Microsoft.NET.CrossGen.targets(501,5): error : Internal.TypeSystem.TypeSystemException+FileNotFoundException: Failed to load assembly 'Microsoft.CodeAnalysis'
   at Internal.TypeSystem.ThrowHelper.ThrowFileNotFoundException(ExceptionStringID id, String fileName) in /_/src/coreclr/tools/Common/TypeSystem/Common/ThrowHelper.cs:line 41

Error Message

{
  "ErrorMessage": "Microsoft.NET.CrossGen.targets(501,5): error : Error: Failed to load assembly 'Microsoft.CodeAnalysis'",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

First build it occurred

Source build 1545314 (2026-08-08); the immediately preceding build 1544010 (2026-08-07) succeeded. The break reproduces in follow-up build 1545712 (2026-08-09).

Duplicate search

Searched open/closed issues and open/merged PRs for Failed to load assembly Microsoft.CodeAnalysis, Compliance.Tests CrossGen, and CrossGen.targets: no existing KBE or fix PR matches this crossgen2 build-break signature. Related runtime (non-build) manifestation of the same missing-assembly root cause on NativeAOT is tracked in #132046.

Filed by ci-failure-scan (detection only). ci-failure-fix walks open [ci-scan] KBEs and either opens a small fix PR or comments here to loop in owners — it never disables the test.

network:
  allowed:
    - defaults
    - "awmgmcpg"

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