BackCompatibilityPublish_Hosted_Works fails with file lock on .gz compression temp

[lewing]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1362100
Build error leg or test failing: Microsoft.NET.Sdk.BlazorWebAssembly.Tests.dll.1
Pull request: #53656

Error Message

{
  "ErrorMessage": "",
  "ErrorPattern": "BlazorWebAssembly\\.5_0\\.targets.*error : The process cannot access the file.*compress.*\\.gz.*because it is being used by another process",
  "BuildRetry": true,
  "ExcludeConsoleLog": false
}

Details

StaticWebAssets_BackCompatibilityPublish_Hosted_Works fails during the legacy .NET 5 compression step (BlazorWebAssembly.5_0.targets line 650) with a file lock on .gz temp files in obj/Debug/net5/compress/. This is the back-compat path for pre-net6.0 WASM clients hosted by a modern server.

The 5_0.targets compression step writes .gz files that may be locked by parallel test execution or antivirus on Windows Helix machines.

Sample error:

Microsoft.NET.Sdk.BlazorWebAssembly.5_0.targets(650,5): error : The process cannot access the file
'...\blazorwasm\obj\Debug\net5\compress\8TBK5+sk.gz' because it is being used by another process.

Sample log: https://helix.dot.net/api/2019-06-17/jobs/1c38b10c-d52a-455c-b028-d52b17e038ea/workitems/Microsoft.NET.Sdk.BlazorWebAssembly.Tests.dll.1/console

Related: #50784, #33956 (similar file lock patterns)

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1362100
Error message validated: [BlazorWebAssembly\.5_0\.targets.*error : The process cannot access the file.*compress.*\.gz.*because it is being used by another process]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 4/1/2026 6:04:17 PM UTC

Report

Summary

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

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[github-actions]

Closed automatically — this Known Build Error has had 0 hits for over a month.