Codex chat fails after “Thinking reconnect 5/5” with 404 Model Not Found error
What version of the Codex App are you using (From “About Codex” dialog)?
Version 26.602.40724 • Released 5 Jun 2026
What subscription do you have?
Plus
What platform is your computer?
_No response_
What issue are you seeing?
While chatting with Codex in the ChatGPT app, the response gets stuck at “Thinking reconnect 5/5” and then fails with the following error:
unexpected status 404 Not Found: Model not found gpt-5.5
Error Details:
URL: https://chatgpt.com/backend-api/codex/responses
CF-Ray: a08a457a7b687fb6-MAA
Request ID: 8ab95f9a-105a-4225-9cdb-bc60dd0ba377
What steps can reproduce the bug?
While chatting with Codex in the ChatGPT app, the response gets stuck at “Thinking reconnect 5/5” and then fails with the following error:
unexpected status 404 Not Found: Model not found gpt-5.5
Error Details:
URL: https://chatgpt.com/backend-api/codex/responses
CF-Ray: a08a457a7b687fb6-MAA
Request ID: 8ab95f9a-105a-4225-9cdb-bc60dd0ba377
Actual Result:
Codex fails after reconnect attempts and returns a 404 model not found error.
Impact:
Unable to continue Codex chat sessions reliably.
What is the expected behavior?
Expected Result:
Codex should continue the chat response normally without reconnect failure.
Additional information
_No response_
4 Comments
Potential duplicates detected. Please review them and close your issue if it is a duplicate.
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Thanks for your patience. The backend issue causing
gpt-5.5requests to return404 Model not foundis now resolved.Please try again. If it still fails, share a fresh request ID and timestamp.
Closing as resolved. If this recurs, please open a new issue with a fresh request ID and timestamp.
same here
unexpected status 404 Not Found: Model not found gpt-5.5, url: https://chatgpt.com/backend-api/codex/responses, cf-ray: a105cb6a0db8378c-MXP, request id: 3fec8468-cba3-4cc8-9878-538f4ab6f8c5