[ci-scan] Build break: SuperPMI asmdiffs browser-wasm — no MCH collection available #132053

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1545358
Build error leg or test failing: SuperPMI asmdiffs checked release windows x64 — browser-wasm work item

Pipeline: runtime-coreclr superpmi-asmdiffs-checked-release (definition 153), branch main. The browser-wasm SuperPMI asmdiffs work item fails because no MCH (method context) collection files are available in Azure Storage for the browser/wasm (x64) target under the current JIT-EE version GUID 305cdd16-2cee-49af-ae7c-2537eb37cae9. The download step finds nothing to fetch, so asmdiffs has no collections to run and the work item exits with code 1. The failure persists into follow-up build 1545748.

Error Details

Running superpmi.py asmdiffs between checked and release binaries
Running: ... superpmi.py asmdiffs --diff_with_release --no_progress -core_root ... -target_os browser -target_arch wasm -arch x64 ...
No Azure Storage MCH files to download from 305cdd16-2cee-49af-ae7c-2537eb37cae9/browser/x64/
No MCH files found to replay

Error Message

{
  "ErrorMessage": [
    "asmdiffs --diff_with_release --no_progress -core_root",
    "No MCH files found to replay"
  ],
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

First build it occurred

Source build 1545358 (2026-08-08); the immediately preceding completed build 1536356 (2026-08-02) succeeded. The signature reproduces in follow-up build 1545748 (2026-08-09).

Duplicate search

Searched open/closed issues and open PRs for superpmi asmdiffs browser wasm MCH and No MCH files found to replay: no existing KBE matches the browser-wasm asmdiffs target. The osx-arm64 superpmi-replay manifestation of the same "no MCH collection available" root cause is tracked separately in #132036 (different pipeline, target, and signature), which does not cover the browser-wasm asmdiffs leg.

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"

Generated by CI Outer-Loop Failure Scanner · 577.8 AIC · ⌖ 17.9 AIC · ⊞ 18.3K · ◷

Report

Summary