codex pc app bug

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

Version 26.616.81150 • Released 2026/06/24

What subscription do you have?

Paid

What platform is your computer?

win11

What issue are you seeing?

Regarding the Codex PC app: it was working without issues until recently.
However, suddenly, the following message began to appear regardless of what I asked.

The 'gpt-5.3-codex' model is not supported when using Codex with a ChatGPT account.

I tried the following:
・Updating Codex
・Uninstalling → Restarting the PC → Reinstalling the latest version
However, the symptoms remain completely unchanged.

To identify the issue, I performed a fresh installation of Codex on a different, new Windows 11 device (one where Codex had never been installed before).
I then authenticated using the exact same account as the device exhibiting the symptoms.
The conversation proceeded smoothly on the new device. It became clear that there were no issues with the account.

The official GPT team needs to address this issue immediately.
If there is an official, effective solution available, please let me know.
Thank you for reading.

What steps can reproduce the bug?

It occurs when you ask a question in a perfectly ordinary way.

What is the expected behavior?

_No response_

Additional information

_No response_