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GPT-5.4 and GPT-5.4 Mini Retire From Codex on August 31

CodexView original changelog

OpenAI announced that GPT-5.4 and GPT-5.4 mini will stop working in Codex for ChatGPT-signed-in users starting August 31, 2026, though both models remain available via the OpenAI API and API-key-authenticated Codex sessions. Codex recommends migrating to GPT-5.6 Terra in place of GPT-5.4 and GPT-5.6 Luna in place of GPT-5.4 mini. The change affects anyone with GPT-5.4 set as a workspace default, saved model preference, managed configuration, custom agent, or scheduled task — all of which should be updated before the cutoff to avoid disruption.

Key Takeaways

  • GPT-5.4 and GPT-5.4 mini will be removed from Codex for ChatGPT-signed-in users on August 31, 2026 — a one-month sunset window from the announcement date.
  • The retirement only affects ChatGPT-authenticated Codex sessions; API-key sessions and direct OpenAI API access to both models are unaffected.
  • OpenAI's recommended migration path swaps GPT-5.4 for GPT-5.6 Terra and GPT-5.4 mini for GPT-5.6 Luna, positioning the newer GPT-5.6 tier as the default going forward.
  • The change lands roughly three weeks after OpenAI cut pricing on GPT-5.6 Luna and Terra (July 30), making the newer models cheaper at the same time they become mandatory replacements.
  • Anything referencing GPT-5.4 by name — workspace defaults, saved model settings, managed configurations, custom agents, and scheduled tasks — will silently break or fall back unless manually updated before the cutoff.
  • This is the latest step in OpenAI's broader push to retire the GPT-5.4 generation in favor of GPT-5.6 Sol/Terra/Luna, following that family's general availability in early July 2026.

Retirement Timeline

Codex published a one-month advance notice that GPT-5.4 and GPT-5.4 mini will be removed as usable models inside Codex for anyone signed in through ChatGPT, effective August 31, 2026. The announcement gives developers and teams a defined window to move saved configurations off the older models before they stop responding.

What's Changing

The retirement is scoped narrowly: it only applies to Codex sessions authenticated through a ChatGPT account. Sessions that authenticate with an OpenAI API key are unaffected, and both GPT-5.4 and GPT-5.4 mini will continue to be reachable directly through the OpenAI API after the cutoff date. In other words, this is a Codex-product-level sunset rather than a full model deprecation across OpenAI's platform.

Recommended Migration Path

Codex's guidance points users toward the newer GPT-5.6 family as the direct replacement: GPT-5.6 Terra takes over for GPT-5.4, and GPT-5.6 Luna takes over for GPT-5.4 mini. The timing lines up with OpenAI's July 30 decision to cut API pricing on both Terra and Luna, meaning the mandated replacements are also now cheaper than they were at GPT-5.6's general availability three weeks earlier — softening the cost impact of the forced migration for heavy Codex users.

Who Is Affected

Because GPT-5.4 has been the default or explicitly selected model in many existing setups, the retirement notice calls out several places developers need to check and update before August 31: workspace-level default models, individually saved model preferences, managed configuration profiles (relevant for teams running Codex under centrally administered settings), custom agents that hard-code a model name, and any scheduled or recurring Codex tasks. Any of these left unchanged will either fail or silently fall back once the cutoff passes, so Codex is framing this as an action item rather than a passive notice.