Windows sandbox helper fails when patching an existing file
What version of the Codex App are you using (From “About Codex” dialog)?
26.715.4045.0
What subscription do you have?
Plus
What platform is your computer?
Microsoft Windows NT 10.0.26200.0 x64
What issue are you seeing?
The Codex Windows app can create a new file, but modifying an existing file with
the normal patch tool fails immediately with windows sandbox: helper_unknown_error.
What steps can reproduce the bug?
Feedback ID: no-active-thread-019f74d1-1792-7a51-88bf-84d438e78a85
- Open a disposable local folder outside Google Drive and outside Git.
- Ask Codex to create test.txt using the normal patch tool.
- File creation succeeds.
- Ask Codex to modify the existing line in test.txt.
- It immediately fails with windows sandbox: helper_unknown_error.
Codex was updated and Windows was fully restarted before repeating the test.
The failure still occurred.
What is the expected behavior?
Codex should modify the existing test.txt file and read back the updated contents without a sandbox/helper error.
Additional information
Actual behavior:
Creating test.txt with the normal patch tool succeeds, but modifying the existing
file immediately fails with:
windows sandbox: helper_unknown_error
I reproduced this in a disposable local folder outside Google Drive and outside
a Git repository. I updated Codex and fully restarted Windows before testing
again. File creation still succeeded, but modification still failed.
Reproduction:
- Open a disposable local folder.
- Ask Codex to create test.txt using the normal patch tool.
- Ask Codex to change the existing line.
- The sandbox helper error occurs immediately.
Feedback ID:
no-active-thread-019f74d1-1792-7a51-88bf-84d438e78a85
3 Comments
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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Important environment difference from #33806:
C:\tmp does not exist on my computer. PowerShell Get-Item and Get-Acl both
return PathNotFound for C:\tmp.
My TEMP environment variable points to C:\temp, not C:\tmp. Despite C:\tmp
being absent, Codex still produces the same windows sandbox
helper_unknown_error when modifying an existing file, while new-file creation
succeeds.
This may be a related variant where the injected <special>:slash_tmp root
cannot be initialized because C:\tmp is absent, rather than because an existing
C:\tmp has the wrong ACL..
Windows sandbox helper write failure
Summary
Sandboxed PowerShell commands fail during sandbox setup, even when targeting
a configured writable workspace. Running the command with sandbox escalation
works immediately.
A similar problem may have occurred on another Windows computer, although its
exact error output still needs comparison.
Environment
Reproduction
New-Item -ItemType Directory -Path '<workspace>\sandbox-write-test' -ForceActual result
The sandboxed shell does not start the command and reports:
windows sandbox: helper_unknown_error: setup refresh had errorsExplicit filesystem permission did not resolve the failure.
Running the directory-creation command outside the sandbox succeeded
immediately. Afterward,
apply_patchsuccessfully created files, while anormal sandboxed PowerShell read still failed with the same helper error.
Expected result
Commands targeting a configured writable workspace should run normally without
requiring sandbox escalation.
Important distinction
One intermediate error about
New-Item -LiteralPathwas a PowerShell commandsyntax issue and is unrelated to the sandbox failure.
Workaround
Use an approved sandbox bypass to create the directory. File editing with
apply_patchmay then work, although normal sandboxed shell commands remainunavailable.
Cross-machine observation
A possibly similar failure occurred on another Windows computer. Confirm by
checking whether its exact error also contains:
windows sandbox: helper_unknown_error: setup refresh had errorsALSO ## Diagnostics019f9e5f-0abe-7a33-8fa1-6640d093a535