Mono WASM test failure with "MONO_WASM: Unhandled error: TypeError: Failed to fetch"

[jakobbotsch]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1396034
Build error leg or test failing: WasmTestOnChrome-MONO-ST-System.Buffers.Tests.WorkItemExecution
Pull request: #127336

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "MONO_WASM: Unhandled error: TypeError: Failed to fetch",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1396034
Error message validated: [MONO_WASM: Unhandled error: TypeError: Failed to fetch]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 4/25/2026 12:25:00 PM UTC

Report

Build	Repository	Test	Pull Request
1423634	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.ReflectionInvokeEmit.Tests.WorkItemExecution	#122056
1422655	dotnet/runtime	WasmTestOnChrome-MONO-ST-Microsoft.Extensions.Configuration.Binder.Tests.WorkItemExecution	#127749
1417725	dotnet/runtime	WasmTestOnChrome-MONO-ST-Microsoft.Extensions.Options.SourceGeneration.Unit.Tests.WorkItemExecution	#128059
1417054	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.ReflectionInvokeInterpreted.Tests.WorkItemExecution	#127762

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
0	0	4

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