Assert failure: IsIL() in TryGenerateAsyncThunk

[jkotas]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1476654
Build error leg or test failing: Interop.WorkItemExecution
Pull request: #129728

Error Message

DO NOT USE JSON BELOW IF THIS IS A BUILD BREAK otherwise build analysis will allow pull requests to merge that break the build worse. For a build break, do not use this issue form. Make a regular new issue.

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

{
  "ErrorMessage": "",
  "ErrorPattern": ["Assert failure.*IsIL","TryGenerateAsyncThunk"],
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1476654
Error message validated: [Assert failure.*IsIL TryGenerateAsyncThunk]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 6/23/2026 12:18:04 PM UTC

Report

Build	Repository	Test	Pull Request
1480623	dotnet/runtime	Interop.WorkItemExecution
1480622	dotnet/runtime	Interop.WorkItemExecution
1480577	dotnet/runtime	Interop.WorkItemExecution	#128702
1480462	dotnet/runtime	Interop.WorkItemExecution
1480432	dotnet/runtime	Interop.WorkItemExecution	#129829
1480431	dotnet/runtime	Interop.WorkItemExecution	#129830
1480435	dotnet/runtime	Interop.WorkItemExecution
1480310	dotnet/runtime	Interop.WorkItemExecution	#129762
1479892	dotnet/runtime	Interop.WorkItemExecution
1479756	dotnet/runtime	Interop.WorkItemExecution	#129605
1478938	dotnet/runtime	Interop.WorkItemExecution
1478711	dotnet/runtime	Interop.WorkItemExecution
1478712	dotnet/runtime	Interop.WorkItemExecution
1478673	dotnet/runtime	Interop.WorkItemExecution
1478674	dotnet/runtime	Interop.WorkItemExecution
1478570	dotnet/runtime	Interop.WorkItemExecution	#129779
1478477	dotnet/runtime	Interop.WorkItemExecution
1476664	dotnet/runtime	Interop.WorkItemExecution
1477894	dotnet/runtime	Interop.WorkItemExecution
1476665	dotnet/runtime	Interop.WorkItemExecution
1476654	dotnet/runtime	Interop.WorkItemExecution	#129728

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
12	21	21

[jkotas]

cc @jakobbotsch

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[jakobbotsch]

Checking, this is failing in a crossgen2 job in one of the COM tests that I added a check for in the VM, perhaps a similar check is needed in crossgen2.