503 Service Unavailable: no healthy upstream when running codex CLI
Resolved 💬 2 comments Opened Mar 2, 2026 by ljubogdan Closed Mar 2, 2026
💡 Likely answer: A maintainer (etraut-openai, contributor)
responded on this thread — see the highlighted reply below.
What version of Codex CLI is running?
codex-cli 0.107.0
What subscription do you have?
ChatGPT Plus
Which model were you using?
gpt-5.3-codex
What platform is your computer?
Linux 6.17.0-14-generic x86_64 x86_64
What terminal emulator and version are you using (if applicable)?
Warp Terminal v0.2026.02.18.08.22.stable_02
What issue are you seeing?
Error output:
Unexpected status 503 Service Unavailable: no healthy upstream
url: https://chatgpt.com/backend-api/codex/responses**
The error appears immediately when the CLI sends the request.
Retrying later does not work.
What steps can reproduce the bug?
- Open terminal
- Run
codex - CLI attempts to call the backend API
- Request fails with HTTP 503
What is the expected behavior?
_No response_
Additional information
_No response_
2 Comments
Looks like upgrading codex to 107 kinda solved the issue temporary for me, but not sure about the definitivity of this workaround. Maybe some system prompts changed without backward compatibility, as even https://status.openai.com/ isn't showing any active issues
Thanks for reporting. This was a temporary server-side issue, and it has been fixed.