What changed
From August 31, 2026, gpt-5.4 and gpt-5.4-mini are unavailable in Codex for anyone signed in with ChatGPT; the OpenAI API and API-key sessions keep them. OpenAI suggested gpt-5.6-terra as the replacement for gpt-5.4 and gpt-5.6-luna for gpt-5.4-mini, and asked users to update workspace defaults, saved settings, managed configs, custom agents and scheduled tasks.
Who it affects
Codex users and admins whose configs or automations pin GPT-5.4 models.
What to do
Search your config.toml, managed settings, agents and scheduled tasks for gpt-5.4 and switch to the matching GPT-5.6 tier.