[Windows 26.825.6671.0] Regression: ChatGPT fails to start with "spawn UNKNOWN" when AppLocker blocks Codex runtime extracted to %LOCALAPPDATA%

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

OpenAI.Codex 26.825.6671.0

What subscription do you have?

Plus

What platform is your computer?

[Microsoft Windows NT 10.0.19045.0 x64]

What issue are you seeing?

The ChatGPT/Codex Microsoft Store application was working normally before the recent update. After updating to 26.825.6671.0, launching ChatGPT immediately fails with:

ChatGPT failed to start
spawn UNKNOWN

ChatGPT Classic continues to launch and work normally.

I investigated the Windows AppLocker logs and found that every attempted launch of the new application generates AppLocker Event ID 8004:

C:\Users\<user>\AppData\Local\OpenAI\Codex\bin\<runtime-id>\codex.exe was prevented from running.

The codex.exe binary itself has a valid Authenticode signature:

Status: Valid
StatusMessage: Signature verified
Signer: CN="OpenAI OpCo, LLC", O="OpenAI OpCo, LLC", L=San Francisco, S=California, C=US

The Microsoft Store application itself is allowed by our AppLocker configuration. The environment permits signed packaged/MSIX applications, but executable execution is separately allow-listed.

The new application appears to extract or deploy its Codex runtime outside the trusted MSIX package location into:

%LOCALAPPDATA%\OpenAI\Codex\bin\<runtime-id>\codex.exe

and subsequently attempts to spawn that executable.

Because %LOCALAPPDATA% is a user-writable location, enterprise AppLocker configurations commonly do not permit arbitrary binaries to execute from it unless an explicit allow rule exists.

As a result:

Microsoft Store ChatGPT package launches
→ ChatGPT attempts to spawn %LOCALAPPDATA%\OpenAI\Codex\...\codex.exe
→ AppLocker blocks codex.exe (Event 8004)
→ spawn UNKNOWN
→ entire ChatGPT application fails to start

What steps can reproduce the bug?

Regression

The application worked on the same enterprise-managed device under the same security controls before the recent Windows app update.

Repair/reset/reinstall will not resolve this case because AppLocker is explicitly denying the relocated runtime executable.

What is the expected behavior?

Expected behaviour / request

Please consider making the Windows MSIX deployment compatible with enterprise AppLocker/WDAC environments by keeping required OpenAI-signed runtime binaries within an appropriate trusted/package-controlled location rather than spawning required executables from user-writable %LOCALAPPDATA%.

Alternatively, the desktop application should degrade gracefully when the Codex runtime cannot start — for example, ChatGPT should still open while displaying that Codex is unavailable due to system policy, rather than causing the entire application to fail at startup.

This is likely to affect other managed enterprise/government Windows environments where Microsoft Store apps are permitted but arbitrary executables from user-writable AppData paths are not.

Additional information

No source files or tests are named. Start by reproducing startup under the reported AppLocker policy and trace the Windows packaged-app startup path through the Codex runtime spawn; done means the application avoids a blocked user-writable runtime location or opens gracefully when Codex is unavailable.