[macOS 26] dotnet dev-certs fails to save HTTPS developer certificate in Helix

[lewing]

Description

WASM Helix work items on osx.26.arm64.open intermittently fail during environment setup when dotnet dev-certs https cannot save the HTTPS developer certificate. The failure occurs before tests execute and has been observed on multiple machines and builds.

Reproduction Steps

Run a browser-wasm library test work item on the osx.26.arm64.open Helix queue. The failure is intermittent and has been confirmed in builds 1586491 and 1584957.

Expected behavior

dotnet dev-certs https completes successfully and the WASM test executes.

Actual behavior

+ dotnet dev-certs https
There was an error saving the HTTPS developer certificate to the current user personal certificate store.
+ export _commandExitCode=2

The subsequent missing xharness-event-processor.py message is secondary to the setup command exiting with code 2.

Regression?

Unknown.

Known Workarounds

Retrying is effective. In build 1584957, the affected work item passed after Helix resubmission.

Configuration

• Queue: osx.26.arm64.open
• Architecture: ARM64
• Confirmed on dci-mac-build-462 running macOS 26.4 and dci-mac-build-480 running macOS 26.4.1
• SDK: 11.0.100-rc.1.26420.103

Other information

This replaces dotnet/dnceng#6723 because the Known Build Error label and Build Analysis automation were unavailable there.

Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1586491
Leg Name: browser-wasm osx Release LibraryTests_SmokeMac - osx.26.arm64.open

Also observed in https://dev.azure.com/dnceng-public/public/_build/results?buildId=1584957 on a different machine, where the affected work item passed after Helix resubmission.

Error Details

+ dotnet dev-certs https
There was an error saving the HTTPS developer certificate to the current user personal certificate store.
+ export _commandExitCode=2

Error Message

{
  "ErrorMessage": "There was an error saving the HTTPS developer certificate to the current user personal certificate store.",
  "BuildRetry": true,
  "ExcludeConsoleLog": false
}

Note

This issue was drafted and filed with GitHub Copilot.

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1586491
Error message validated: [There was an error saving the HTTPS developer certificate to the current user personal certificate store.]
Result validation: ❌ Known issue did not match with the provided build.
Validation performed at: 9/8/2026 7:25:27 PM UTC

Report

Build	Repository	Test	Pull Request
1612733	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Tests.WorkItemExecution
1611974	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Intrinsics.Tests.WorkItemExecution
1611907	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Linq.Tests.WorkItemExecution
1611548	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Tests.WorkItemExecution
1611331	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Tests.WorkItemExecution
1611296	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.InteropServices.JavaScript.Tests.WorkItemExecution
1611095	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Intrinsics.Tests.WorkItemExecution
1610317	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.InteropServices.JavaScript.Tests.WorkItemExecution
1609928	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.InteropServices.JavaScript.Tests.WorkItemExecution
1609313	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Linq.Tests.WorkItemExecution
1606964	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Linq.Tests.WorkItemExecution
1602939	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Tests.WorkItemExecution
1598865	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Intrinsics.Tests.WorkItemExecution
1598671	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Tests.WorkItemExecution	#130050
1598095	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Intrinsics.Tests.WorkItemExecution
1596425	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.InteropServices.JavaScript.Tests.WorkItemExecution
1594788	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Intrinsics.Tests.WorkItemExecution
1593453	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Tests.WorkItemExecution
1591427	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Tests.WorkItemExecution	#130050
1590497	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Intrinsics.Tests.WorkItemExecution
1589719	dotnet/runtime	WasmTestOnChrome-MONO-ST-System.Runtime.Intrinsics.Tests.WorkItemExecution
1586600	dotnet/runtime	WasmTestOnChrome-ST-System.Runtime.Extensions.Tests.WorkItemExecution	#133391
1586573	dotnet/runtime	WasmTestOnFirefox-ST-System.Net.WebSockets.Tests.WorkItemExecution	#133388
1586559	dotnet/runtime	WasmTestOnV8-ST-System.Linq.Queryable.Tests.WorkItemExecution	#133387
1586540	dotnet/runtime	normal-System.Formats.Asn1.Tests.WorkItemExecution	#133386

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
0	11	25

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