What version of the Codex App are you using (From “About Codex” dialog)?
26.803.41515
What subscription do you have?
ChatGPT Pro
What platform is your computer?
Linux 7.0.0-28-generic x86_64 x86_64
What issue are you seeing?
GPT-5.6 Pro does not work in Chat mode. The problem is not limited to one entry point: Pro is unusable everywhere Chat mode is available, including the Codex desktop app and ChatGPT on the web.
Selecting GPT-5.6 Pro and sending a prompt does not start a usable Pro response. The issue reproduces consistently across conversations and surfaces, so Chat mode currently has no working way to use the Pro model.
What steps can reproduce the bug?
- Open Chat mode in the Codex desktop app.
- Select GPT-5.6 Pro.
- Send any prompt.
- Observe that the Pro request does not produce a usable response.
- Repeat the same steps in ChatGPT on the web or another Chat-mode entry point.
The result is the same everywhere: GPT-5.6 Pro is unusable in Chat mode.
What is the expected behavior?
GPT-5.6 Pro should start normally in Chat mode and return a complete Pro response on every supported surface.
Additional information
This is not isolated to a specific prompt or conversation.
A related issue, #34015, reports possible silent fallback or reduced reasoning quality. This report covers a broader failure mode: GPT-5.6 Pro is not usable in Chat mode at all, on any surface tested.
What version of the Codex App are you using (From “About Codex” dialog)?
26.803.41515
What subscription do you have?
ChatGPT Pro
What platform is your computer?
Linux 7.0.0-28-generic x86_64 x86_64
What issue are you seeing?
GPT-5.6 Pro does not work in Chat mode. The problem is not limited to one entry point: Pro is unusable everywhere Chat mode is available, including the Codex desktop app and ChatGPT on the web.
Selecting GPT-5.6 Pro and sending a prompt does not start a usable Pro response. The issue reproduces consistently across conversations and surfaces, so Chat mode currently has no working way to use the Pro model.
What steps can reproduce the bug?
The result is the same everywhere: GPT-5.6 Pro is unusable in Chat mode.
What is the expected behavior?
GPT-5.6 Pro should start normally in Chat mode and return a complete Pro response on every supported surface.
Additional information
This is not isolated to a specific prompt or conversation.
A related issue, #34015, reports possible silent fallback or reduced reasoning quality. This report covers a broader failure mode: GPT-5.6 Pro is not usable in Chat mode at all, on any surface tested.