tvos-arm64 Mono AOT precompilation fails with Invalid IL code for multiple test assemblies

[kotlarmilos]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1362636
Build error leg or test failing: System.Net.NameResolution.Functional.Tests.WorkItemExecution, System.Reflection.Context.Tests.WorkItemExecution, System.Text.Encoding.Extensions.Tests.WorkItemExecution
Pull request: #125441

Affected CI jobs: build_tvos_arm64_Release_AllSubsets_Mono

Error Message

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

{
  "ErrorMessage": "Precompiling failed",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Summary

On tvos-arm64 Mono Release (AOT mode), the Mono AOT compiler fails to precompile test assemblies with "Invalid IL code" errors:

Precompiling failed for aot-instances.dll with exit code 134
Unable to compile method ... due to: 'Invalid IL code in ...: IL_0000: ret'

3 work items affected:

• System.Net.NameResolution.Functional.Tests
• System.Reflection.Context.Tests
• System.Text.Encoding.Extensions.Tests

Note

This issue was filed with the assistance of GitHub Copilot.

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1362636
Error message validated: [Precompiling failed]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 4/2/2026 10:17:08 AM UTC

Report

Build	Repository	Test	Pull Request
1510254	dotnet/runtime	System.IO.Hashing.Tests.WorkItemExecution
1507086	dotnet/runtime	iOS.Device.Aot.Test.WorkItemExecution
1507089	dotnet/runtime	iOS.Device.Aot.Test.WorkItemExecution
1507280	dotnet/runtime	System.Runtime.Tests.WorkItemExecution	#130651
1499665	dotnet/runtime	IcuAppLocal.Tests.WorkItemExecution
1505679	dotnet/runtime	System.Runtime.Tests.WorkItemExecution	#130356
1505016	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.WorkItemExecution
1499642	dotnet/runtime	iOS.Device.ExportManagedSymbols.Test.WorkItemExecution
1499248	dotnet/runtime	iOS.Device.Aot.Test.WorkItemExecution	#130346
1502946	dotnet/runtime	iOS.Device.ExportManagedSymbols.Test.WorkItemExecution	#130356
1501202	dotnet/runtime	System.ComponentModel.Annotations.Tests.WorkItemExecution
1500857	dotnet/runtime	iOS.Device.ExportManagedSymbols.Test.WorkItemExecution	#130342
1499481	dotnet/runtime	iOS.Device.ExportManagedSymbols.Test.WorkItemExecution	#130356
1499030	dotnet/runtime	System.Diagnostics.Debug.Tests.WorkItemExecution
1495180	dotnet/runtime	Microsoft.Extensions.FileProviders.Physical.Tests.WorkItemExecution
1495192	dotnet/runtime	System.Globalization.Calendars.Tests.WorkItemExecution
1494925	dotnet/runtime	System.Runtime.Tests.WorkItemExecution	#130235
1486312	dotnet/runtime	System.Data.Common.Tests.WorkItemExecution
1485789	dotnet/runtime	System.Data.Common.Tests.WorkItemExecution
1485187	dotnet/runtime	Microsoft.Extensions.DependencyModel.Tests.WorkItemExecution
1483966	dotnet/runtime	System.Data.Common.Tests.WorkItemExecution
1483740	dotnet/runtime	System.Diagnostics.TextWriterTraceListener.Tests.WorkItemExecution
1472657	dotnet/runtime	System.Diagnostics.TextWriterTraceListener.Tests.WorkItemExecution
1472667	dotnet/runtime	System.Runtime.Tests.WorkItemExecution

Summary

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

[dotnet-policy-service]

Tagging subscribers to 'os-tvos': @vitek-karas, @kotlarmilos, @steveisok, @akoeplinger
See info in area-owners.md if you want to be subscribed.

[BrzVlad]

@kotlarmilos Any idea about this ? I seem to remember you fixed something similar at some point, with the issue being that we were passing the wrong processed assemblies to the compiler, some issue on the infrastructure side.

Looking at some logs seems like this might match on unrelated issues. Ex:

/tmp/helix/working/9699087B/p/build/apple/AppleBuild.targets(260,5): error : Precompiling failed for /tmp/helix/working/9699087B/w/B61009D4/e/publish/JsonSchema.Net.dll with exit code 1. [/private/tmp/helix/working/9699087B/w/B61009D4/e/publish/ProxyProjecUnhandled exception: Unhandled exception: No space left on device

[kotlarmilos]

This happens on Helix retries. I think the ILLinker runs on the first attempt, and if the job fails, it tries trimming again on the same payload, which has already been trimmed. Although the error message is too generic