Codex Desktop: all ChatGPT-account models unavailable (GPT-5.5 404; GPT-5.4/5.3 unsupported)

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

26.602.71036

What subscription do you have?

ChatGPT Plus ($20/month)

What platform is your computer?

No response

What issue are you seeing?

Feedback ID: 019fd4ce-66fc-71f0-8a80-75fb6a056e3a

Codex Desktop suddenly fails on every chat although my ChatGPT Plus subscription and Codex usage allowance are active.

GPT-5.5 returns:
“unexpected status 404 Not Found: The model gpt-5.5 does not exist or you do not have access to it.”

GPT-5.4 returns:
“The gpt-5.4 model is not supported when using Codex with a ChatGPT account.”

GPT-5.3-Codex returns the same unsupported-model error.

The model picker only shows these legacy models. I signed out and back in, fully quit the app, restarted Windows, and tried multiple chats. Please refresh/fix the model catalog or entitlement for my ChatGPT account.

Request IDs:
14127c0c-fb7e-4b8b-8e0c-7d7bedf80da9
bb63d41d-37bf-4daa-8935-43e2a10b10b1

What steps can reproduce the bug?

1. Open Codex Desktop on Windows and sign in with my ChatGPT Plus account.
2. Open any existing chat or start a new chat.
3. Send any prompt, for example: “test”.
4. With GPT-5.5 selected, Codex retries reconnecting and returns a 404 model-access error.
5. Change the model to GPT-5.4 and send a prompt again.
6. Codex returns: “The gpt-5.4 model is not supported when using Codex with a ChatGPT account.”
7. Change the model to GPT-5.3-Codex and send a prompt again.
8. Codex returns the same unsupported-model error.

This happens in every chat, including newly created chats.

What is the expected behavior?

Codex Desktop should display at least one currently supported model for ChatGPT Plus accounts and successfully generate a response.

If a model is no longer supported, it should not appear as an available option in the model picker. The app should refresh its model catalog automatically instead of showing legacy models that all fail.

Additional information

This started suddenly while Codex had been working normally earlier the same day. No changes were made to my account, subscription, computer, or configuration.

My ChatGPT Plus subscription is active and the Codex usage page shows remaining allowance (21% of the 5-hour limit and 86% of the weekly limit at the time of the issue).

I also submitted in-app feedback:
Feedback ID: 019fd4ce-66fc-71f0-8a80-75fb6a056e3a

I will attach screenshots showing the model picker, the GPT-5.5 404 error, and the GPT-5.4 unsupported-model error.

No source files or tests are identified. Reproduce on Windows with a ChatGPT Plus account, then trace the desktop model picker and account model-catalog or entitlement handling using the supplied model names and request IDs. Done means at least one supported model is shown and generates a response, while unsupported models are omitted or refreshed.