Codex 5.4 / 5.3-codex models fail with “not supported for ChatGPT account” error

[hjkim0015]

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

26.305.950(863)

What subscription do you have?

Pro

What platform is your computer?

mac os | Darwin 25.3.0 arm64 arm

What issue are you seeing?

When selecting gpt-5.4 or gpt-5.3-codex in the Codex app, requests fail with the following error:
{"detail":"The 'gpt-5.3-codex' model is not supported when using Codex with a ChatGPT account."}

What steps can reproduce the bug?

1. Open the Codex app
2. Select the gpt-5.4 or gpt-5.3-codex model
3. Send any prompt
4. The request fails with the error above

Prompt: "hello"
Response error:
{"detail":"The 'gpt-5.3-codex' model is not supported when using Codex with a ChatGPT account."}

What is the expected behavior?

The Codex app should allow using gpt-5.4 and gpt-5.3-codex normally.
If these models are not available for ChatGPT accounts, they should be hidden/disabled in the model list or show a clear availability message before sending.

Additional information

No response

[github-actions]

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

• The ('gpt-5.4', 'gpt-5.3-codex') model is not supported when using Codex with a ChatGPT account. #14181

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[egormaksgrom2706-create]

How did you decide that? Can you help?

[hjkim0015]

After the error occurred, the 5.4 version briefly disappeared from the Codex app. It became available again about 10 minutes later, and the issue was closed after confirming normal operation.

[Glenn-Domin]

That's interesting. If it came back without you having to do anything I think that confirms what others have suspected, that this is an issue on the server side.