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_