Cannot find the specified module codex-windows-sandbox-setup.exe

[Jiuxiao-yunwai]

What version of the Codex App are you using (From “About Codex” dialog)?

26.616.32156

What subscription do you have?

plus

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

找不到指定的模块 codex-windows-sandbox-setup.exe

019edfe9-d109-7920-a40d-0e8cc3df7e30

What steps can reproduce the bug?

Feedback ID: 019edfe9-d109-7920-a40d-0e8cc3df7e30

What is the expected behavior?

No response

Additional information

No response

[github-actions]

English translation:

What version of the Codex App are you using (From “About Codex” dialog)?

26.616.32156

What subscription do you have?

plus

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

Cannot find the specified module codex-windows-sandbox-setup.exe

019edfe9-d109-7920-a40d-0e8cc3df7e30

What steps can reproduce the bug?

Feedback ID: 019edfe9-d109-7920-a40d-0e8cc3df7e30

What is the expected behavior?

No response

Additional information

No response

[github-actions]

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

• Windows Codex App: apply_patch fails because codex-windows-sandbox-setup.exe cannot launch from package path #29072
• Windows app 26.616.3309.0: native sandbox setup helper fails with “The specified module could not be found #28982
• Windows app 26.616.3767.0: elevated sandbox setup helper still fails with “The specified module could not be found” #29053

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[JJjyJJ7F3]

same here, quite annoying

[Onlydreams]

I can reproduce the same codex-windows-sandbox-setup.exe dialog, and I think there is a clearer root-cause / graceful-degradation case here.

Environment

• Codex Desktop MSIX package: OpenAI.Codex_26.616.6631.0_x64__2p2nqsd0c76g0
• Helper path shown in the Windows dialog:
  C:\Program Files\WindowsApps\OpenAI.Codex_26.616.6631.0_x64__2p2nqsd0c76g0\app\resources\codex-windows-sandbox-setup.exe
• OS from systeminfo:
  Microsoft Windows 11 Home, 10.0.26200, x64
• Windows dialog text, zh-CN:
  找不到指定的模块。
  Equivalent: The specified module could not be found.

The helper executable exists on disk. Its static import table only references normal Windows DLLs such as KERNEL32.dll, advapi32.dll, user32.dll, ws2_32.dll, etc.; no obvious third-party runtime DLL is missing.

Key finding

On this machine, Windows Sandbox is not just disabled. The feature is unknown to the OS image:

dism.exe /Online /Get-FeatureInfo /FeatureName:Containers-DisposableClientVM

Output:

Error: 0x800f080c
Feature name Containers-DisposableClientVM is unknown.
A Windows feature name was not recognized.

This matches the machine being Windows 11 Home, where the Windows Sandbox feature is not available in the image.

Current behavior

Codex still tries to launch:

app\resources\codex-windows-sandbox-setup.exe

Then Windows shows the raw loader dialog:

The specified module could not be found.

The user gets no actionable message explaining that Windows Sandbox is unavailable on this edition/image.

Expected behavior

Codex should detect this before launching the sandbox setup helper:

• Check whether Containers-DisposableClientVM / the required Windows sandbox capability exists and is enabled.
• If the capability is unavailable, do not launch codex-windows-sandbox-setup.exe in a way that produces a raw Windows modal error.
• Gracefully degrade by disabling only sandbox-dependent functionality, or fall back to a non-sandbox path where safe.
• Show a clear Codex-level diagnostic, for example:
  Windows Sandbox is not available on this Windows edition/image. Some sandbox-dependent Codex Desktop features are unavailable.

This issue is less about making Windows Home support Windows Sandbox, and more about Codex handling unsupported Windows environments cleanly instead of surfacing an opaque native Windows error dialog.

[Lggyy9]

I was able to fix this issue on my machine.

Environment:

• Windows 11 Home
• Codex Desktop App: OpenAI.Codex_26.616.6631.0_x64__2p2nqsd0c76g0
• Error dialog: codex-windows-sandbox-setup.exe / “The specified module could not be found.”

In my case, the problem was related to the proxy settings stored in Codex’s user directory.

I had proxy variables configured in:

C:\Users\<username>\.codex\.env

For example:

HTTP_PROXY="http://127.0.0.1:7897"
HTTPS_PROXY="http://127.0.0.1:7897"
ALL_PROXY="socks5://127.0.0.1:7897"

And the sandbox state file also had the same proxy port recorded:

C:\Users\<username>\.codex\.sandbox\setup_marker.json

Before:

"proxy_ports": [
  7897
]

What fixed it for me:

1. Close Codex completely.
2. Rename .env to .env.bak, or remove/comment out the proxy variables.
3. Edit .codex\.sandbox\setup_marker.json.
4. Change proxy_ports to an empty array:

"proxy_ports": []

5. Restart Codex.

After doing this, Codex stopped launching codex-windows-sandbox-setup.exe, and file editing / apply_patch started working again.

So this seems to be related to a mismatch between proxy settings in .codex\.env and the Windows elevated sandbox state in .codex\.sandbox\setup_marker.json.

For users who still need a proxy, using a system-level/TUN proxy mode may be safer than setting HTTP_PROXY, HTTPS_PROXY, or ALL_PROXY directly in Codex’s .env until this bug is fixed.