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[release/10.0] Add ERROR_NETNAME_DELETED to IsPathUnreachableError for Windows localhost removal - #124869
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Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>
AaronRobinsonMSFT
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jozkee added a commit
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…ue for UNC paths (#124906) Backport of #124867 to release/8.0 /cc @jozkee @Copilot ResolveLinkTarget_Succeeds fails with IOException: The specified network name is no longer available on Windows versions that have UNC access disabled, because SymbolicLink_ResolveLinkTarget_PathToTarget_Data was yielding UNC paths with returnFinalTarget=true, causing Windows to actually attempt to resolve \\LOCALHOST\share\path. Test only change for 8.0 (and 9.0), for 10.0 we backported the fix: #124869. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: jozkee <16040868+jozkee@users.noreply.github.com>
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Backport of #121569 to release/10.0
/cc @jozkee@copilot
Customer Impact
This only affects
ResolveLinkTarget(returnFinalTarget: true). Code first tries to open the final file viaOpenSafeFileHandleas an optimized approach, and when that fails it checks IsPathUnreachableError to decide whether to fall back to manually traversal withDeviceIoControl. SinceERROR_NETNAME_DELETEDwas not being categorized as a path unreachable error, the fallback never happens and anIOExceptionis thrown instead.We don't have customer reports yet, but we expect them to come eventually, and this is technically a
regression-from-last-release.Regression
This is a regression caused by a Windows OS update that removed localhost support. The error started appearing in CI builds around October 2025.
Testing
The original PR #121569 was merged to main on November 13, 2025 and resolved the CI failures.
Risk
Low. The change adds a single error code constant (ERROR_NETNAME_DELETED = 0x40) and includes it in the existing
IsPathUnreachableErrorpattern match alongside other similar network path error codes (ERROR_BAD_NETPATH, ERROR_BAD_NET_NAME, ERROR_NETWORK_ACCESS_DENIED, etc.)