2026-04-22 04:09:27
GPT-5.5 Appears in OpenAI Codex Selector but Returns 400 Error, Currently Unavailable
Gate News message, April 22 — GPT-5.5 has appeared in the model selector dropdown for OpenAI Codex, positioned at the top of the list.
However, when users select GPT-5.5 and submit a request, Codex returns a 400 error with the message "The 'gpt-5.5' model is not supported when using Codex with a Ch