codex - 💡(How to fix) Fix Codex Windows App fails to start: app-server websocket closed, code=3221225501

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

OpenAI.Codex_26.13.4821.0_x64__2p2nqsd0c76g0

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64 Windows 11 25H2, OS build 26200.8457 CPU: Intel(R) Core(TM) Ultra 5 125H

What issue are you seeing?

Codex Windows App fails to start. The app opens but then crashes with:

(code=3221225501, signal=null) Most recent error: Codex app-server websocket closed (code=3221225501)

Windows Reliability Monitor reports Codex.exe stopped responding with MoAppHang.

Environment:

• Codex App version: OpenAI.Codex_26.13.4821.0_x64
• Windows platform command output: Microsoft Windows NT 10.0.26200.0 x64
• Windows version from winver: Windows 11 25H2, OS build 26200.8457
• CPU: Intel(R) Core(TM) Ultra 5 125H
• Git installed at: C:\Program Files\Git\cmd\git.exe
• Git verified successfully with: where.exe git git --version
• Region/network: China network environment. Tested with VPN off, WireGuard VPN, and StealthVPN.

Reliability Monitor details:

• Problem: Stopped responding and was closed
• Problem Event Name: MoAppHang
• Package Full Name: OpenAI.Codex_26.13.4821.0_x64__2p2nqsd0c76g0
• Application Name: praid:App
• Application Version: 2886.0.0.0
• OS Version: 10.0.26200.2.0.0.768.99
• Locale ID: 2052

Expected behavior: Codex App should start normally and show the main interface.

Actual behavior: Codex App crashes or stops responding with: Codex app-server websocket closed (code=3221225501)

What steps can reproduce the bug?

Steps to reproduce:

1. Install Git for Windows to the default path: C:\Program Files\Git

2. Verify Git works in PowerShell: where.exe git git --version

3. Install Codex Windows App from Microsoft Store / winget.

4. Open Codex App.

5. The app starts briefly, then shows: Codex app-server websocket closed (code=3221225501)

Troubleshooting already tried:

• Clean uninstall and reinstall via Microsoft Store / winget
• Deleted old .codex, .cache/codex-runtimes, and .copilot remnants
• Reinstalled Git to default C:\Program Files\Git path
• Confirmed Git works in PowerShell
• Confirmed WSL run option is disabled
• Tested VPN off, WireGuard VPN, and StealthVPN
• Application Filter set to tunnel all apps
• Tried WireGuard keep-alive 25 seconds
• Installed/repaired Microsoft Visual C++ Redistributable 2015–2022 x64
• Installed/repaired Microsoft Edge WebView2 Runtime
• Checked Windows Reliability Monitor
• Tried config.toml with:

git_binary = "C:/Program Files/Git/cmd/git.exe"

[windows] sandbox = "elevated" sandbox_private_desktop = false

• Also tried:

[windows] sandbox = "unelevated" sandbox_private_desktop = false

• Disabled browser plugin:

[plugins."browser@openai-bundled"] enabled = false

Result: Codex App still crashes with the same app-server websocket closed error.

What is the expected behavior?

Codex App should start normally, keep the app-server running, and show the main interface without crashing or closing the websocket connection.

Additional information

I am located in China, so I tested multiple network conditions:

• VPN off
• WireGuard VPN
• StealthVPN
• VPN application filter set to tunnel all apps

The issue happens in all cases. Sometimes the app does not show the error immediately after reconnecting VPN, but after a short time it still fails with the same app-server websocket closed error.

I also checked Windows Reliability Monitor. It reports Codex.exe as MoAppHang rather than showing a clear DLL faulting module.

<img width="1962" height="1006" alt="Image" src="https://github.com/user-attachments/assets/b08d49af-f24b-46ea-a773-5737b0b3db06" />