Windows Codex app-server crashes with 0xC000001D

ChatGPT Bugs
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1

Hello. I’m seeing a persistent Windows-native Codex failure and wanted to check whether anyone else is experiencing the same issue.

System

  • Windows 11 25H2, build 26200
  • Intel Core Ultra 5 226V
  • Latest ChatGPT/Codex desktop app tested
  • Codex standalone CLI 0.150.1
  • Official Codex VS Code extension
  • I need to use Astrill VPN to access ChatGPT from my location

Behaviour
ChatGPT Classic works normally on the same PC, with the same account and VPN connection.

The problem only affects the newer ChatGPT desktop app/Codex stack.

The new app opens with “Hit a snag”, and sign-in then fails with:

Sign-in failed: Codex app-server process is not available

The Codex VS Code extension also loads its panel, but the backend dies during initialisation.

Logs consistently show the Codex app-server exiting with:

3221225501 (0xC000001D)

which corresponds to:

STATUS_ILLEGAL_INSTRUCTION

The app-server can briefly initialise/connect before the process terminates.

Troubleshooting already tried

  • Updated/reinstalled the new ChatGPT/Codex Windows app

  • Tested the standalone Codex CLI rather than only the bundled desktop runtime

  • Confirmed codex --version works

  • Confirmed the app can spawn the Codex app-server before it crashes

  • Tested both the desktop app and official VS Code extension — same 0xC000001D failure

  • Checked NTFS permissions, Defender threat history, AppLocker and Code Integrity logs — no obvious block

  • Tested a clean/minimal ~/.codex/config.toml

  • Tested:

    [windows]
sandbox = "unelevated"
sandbox_private_desktop = false

  • Tried normal ChatGPT authentication and codex login --device-auth

  • Device authentication also terminates with exit code -1073741795, which is the signed form of 0xC000001D

I do need Astrill VPN to access ChatGPT, so I initially considered that as a possible cause. However, ChatGPT Classic works reliably over the same VPN connection, and the Codex failure appears to be a local native-process crash rather than simply a connectivity failure.

The CLI also executes basic commands successfully before hitting the failing code path, so at this stage I do not think the VPN is the root cause, although it could still affect authentication/network behaviour separately.

At this point I’m considering WSL2 as a workaround, but ideally I would like to get the native Windows desktop and VS Code Codex integration working.

Has anyone else seen this specific 0xC000001D / STATUS_ILLEGAL_INSTRUCTION crash, particularly on Intel Core Ultra / Lunar Lake hardware or Windows 11 25H2?

If so, did a particular Codex build, Windows update, sandbox setting, or other workaround resolve it?

Thanks.

2

Welcome to the forum!

You are welcome to discuss Codex issues here. However, the official place to report and track Codex bugs is the OpenAI Codex GitHub issue tracker.

I asked ChatGPT to search for the closest related issue, and it identified:

If that issue describes the same problem you are experiencing, consider adding a :+1: reaction to the GitHub issue itself, rather than only reacting to this forum topic. GitHub reactions can help the maintainers gauge how many users are affected.

If it does not match your problem closely enough, search the existing Codex issues for a better match. If you cannot find one, consider opening a new issue and include as much relevant information as possible, such as your Codex version, operating system, environment, reproduction steps, expected behavior, actual behavior, and any relevant logs or error messages.