Windows Store build 26.721.11231.0 exits during native bootstrap and sandbox setup on multiple Windows profiles

Summary

This report concerns the Codex/ChatGPT Windows desktop application distributed through Microsoft Store, package OpenAI.Codex, not the Codex CLI.

The current Microsoft Store build repeatedly becomes completely unlaunchable:

Package: OpenAI.Codex
Version: 26.721.11231.0
Store product ID: 9PLM9XGG6VKS
Windows: 10.0.19045.7548 x64

A fresh Procmon trace shows ChatGPT.exe:

• starts from the correct Microsoft Store package path,
• loads only ChatGPT.exe and ntdll.dll,
• consumes effectively zero user and kernel CPU time,
• exits in approximately 0.26–0.28 seconds,
• and returns 0xC0000001 (STATUS_UNSUCCESSFUL).

A separate clean Windows profile reached the first-run permission stage, launched:

codex-windows-sandbox-setup.exe

and then displayed:

The application is exiting and cannot service this request

This rules out the primary profile's recovered chats, .codex state, Electron profile, OpenAI runtime folder, and AppX user-data container as sufficient explanations.

Exact visible errors

Primary launch failure:

C:\Program Files\WindowsApps\OpenAI.Codex_26.721.11231.0_x64__2p2nqsd0c76g0\app\ChatGPT.exe

The application is exiting and cannot service this request

Clean-profile first-run setup:

Finish Windows setup

ChatGPT needs a one-time permission to work on your computer

Sandbox helper failure:

C:\Program Files\WindowsApps\OpenAI.Codex_26.721.11231.0_x64__2p2nqsd0c76g0\app\resources\codex-windows-sandbox-setup.exe

The application is exiting and cannot service this request

Reproduction and repair attempts already completed

The failure survives:

• direct AppX removal with Remove-AppxPackage -AllUsers,
• reinstall through winget,
• reinstall through the Microsoft Store UI,
• clean AppX user-data container,
• moved-aside %APPDATA%\Codex,
• moved-aside %LOCALAPPDATA%\OpenAI\Codex,
• preserved but separately tested %USERPROFILE%\.codex,
• a separate Windows account,
• manually starting ClipSVC,
• Windows integrity checks,
• signature verification,
• compatibility-layer checks,
• Exploit Protection checks,
• Defender, AppLocker, Code Integrity, AppModel, TWinUI, Shell-Core, and WER inspection.

The Store package reports:

Status: Ok
Signature: Valid

The Store currently supplies only the same failing version:

26.721.11231.0

Procmon findings

Two fresh launch attempts:

Attempt 1
Start: 5:50:42.2525421 PM
Exit:  5:50:42.5338560 PM
Elapsed: ~0.281 seconds
Exit status: 0xC0000001

Attempt 2
Start: 5:50:51.6888074 PM
Exit:  5:50:51.9515156 PM
Elapsed: ~0.263 seconds
Exit status: 0xC0000001

Loaded images before exit:

ChatGPT.exe
ntdll.dll

No normal Chromium/Electron initialization occurs.

ProcDump found no catchable exception. The process exits before a termination dump can be written.

Dependency inspection

ChatGPT.exe declares:

chrome_elf.dll
VERSION.dll
KERNEL32.dll
ntdll.dll

chrome_elf.dll exists and depends only on standard Windows DLLs.

codex-windows-sandbox-setup.exe also depends only on standard Windows libraries and declares:

Machine: x64
Operating system version: 6.00
Subsystem version: 6.00

There is no obvious missing third-party DLL or declared Windows-version incompatibility.

Hardware compatibility context

CPU:

AMD A8-5500 APU
x86-64-v2 supported
AVX supported
AVX2 not supported
BMI2 not supported
MOVBE not supported

This is relevant compatibility context, but the observed exit is 0xC0000001, not an illegal-instruction exception, and this same build previously ran temporarily on this machine.

Suspected recurrence trigger

The two most recent recurrences occurred while two or three chats/tasks were active simultaneously.

The PC remained responsive and system performance was monitored.

Please test:

• two and three simultaneous chats,
• concurrent tool execution,
• multiple active workspace roots,
• forced close with several active tasks,
• restart after interrupted concurrent work,
• and sandbox initialization after multi-task activity.

Full postmortem and sanitized evidence

Full technical postmortem:

https://github.com/phillipnhenry/chatgpt-windows-app-postmortem/blob/main/ChatGPT-Windows-App-A-Postmortem.md

Sanitized evidence ZIP:

https://github.com/phillipnhenry/chatgpt-windows-app-postmortem/blob/main/evidence/ChatGPT-Codex-Public-Evidence-SANITIZED-20260730.zip

Repository:

https://github.com/phillipnhenry/chatgpt-windows-app-postmortem

Requested engineering action

Please provide:

1. An engineering bug ID.
2. The affected build range.
3. The root cause of 0xC0000001.
4. The root cause of the codex-windows-sandbox-setup.exe failure.
5. A supported limited-access/no-sandbox fallback.
6. Startup diagnostics before Chromium initialization.
7. A fixed Store version or rollback path.
8. Testing on Windows 10 build 19045 and x86-64-v2 CPUs.
9. Testing under multiple Windows profiles.
10. Testing multiple simultaneous chats/tasks.

The current Store package should be suspended or replaced until a verified build is available.