[ci-scan] Test failure: browser-wasm R2R interpreter-to-R2R thunk traps with null function or function signature mismatch

[github-actions]

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1588256
Build error leg or test failing: coreclr Pri1 Runtime Tests Run browser wasm checked - LoaderClassloaderGenerics / Regressions / Regression_NoOptimize_r_1 work items

Multiple browser-wasm CoreCLR R2R runtime-test work items trap in the interpreter-to-R2R transition thunk. The crash surfaces as RuntimeError: null function or function signature mismatch with WasmInterpreterToR2RThunk / WasmUnboxingStub frames on the wasm stack, aborting the merged test runner (exit 1). Observed across consecutive runtime-coreclr outerloop builds on main (1588256, 1588672) and across several work items per build. This is distinct from the platform-incompatibility failures tracked by #133259 and belongs to the in-development browser-wasm R2R lane (tracking #130524).

KBE authoring guidance (ci-failure-scan)

• Error Details is for readers. Paste the full exception, stack trace, or build error excerpt so the failure is understandable without opening the raw log.
• Build Analysis parses only the single JSON block under Error Message.
• ErrorMessage is a case-sensitive ordinal String.Contains substring copied verbatim from the failing log.
• Set BuildRetry to true only for a clear infrastructure retry case. ExcludeConsoleLog disables Helix console-log scanning.

Error Details

RuntimeError: null function or function signature mismatch
    at WasmUnboxingStub(UGviiii) ((wasm/redacted)
    at WasmInterpreterToR2RThunk(vTS1p) ((wasm/redacted)
    at (wasm/redacted)
    ...
    at WasmR2RToInterpreterThunk(iip) ((wasm/redacted)
    at S_P_CoreLib_System_Environment__CallEntryPoint ((wasm/redacted)

Error Message

{
  "ErrorMessage": [
    "RuntimeError: null function or function signature mismatch",
    "WasmInterpreterToR2RThunk"
  ],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Agentic workflow metadata (ci-failure-scan)

Workflow artifact: ci-failure-scan
Artifact kind: kbe-verification
Verified match count: 1 hits in failure.log

---

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.

Generated by CI Outer-Loop Failure Scanner · opus48 · 994 AIC · ⌖ 17.9 AIC · ⊞ 19.5K · ◷

Report

Build	Repository	Test	Pull Request
1589561	dotnet/runtime	Regressions.WorkItemExecution

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
1	1	1

[lewing]

@davidwrighton this appears to be from #133218 I have a local fix I'll put up as draft

[lewing]

4. @davidwrighton this appears to be from #133218 I have a local fix I'll put up as draft

Actually, I don't like it. I'll let you take a look.

[lewing]

5. > 4. @davidwrighton this appears to be from #133218 I have a local fix I'll put up as draft

Actually, I don't like it. I'll let you take a look.

#133516