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Codex Retires GPT-5.5 for ChatGPT Sign-In Users, Points to GPT-6.1 Sol

CodexView original changelog

OpenAI removed GPT-5.5 from Codex for users signed in with ChatGPT on October 14, 2026, at noon PDT (19:00 UTC). API-key sessions and the OpenAI API are not affected. OpenAI suggests GPT-6.1 Sol (gpt-6.1-sol) as the replacement where it is available for a plan and client. Teams should update any defaults, settings, agents, scheduled tasks and scripts that still select GPT-5.5.

Key Takeaways

  • GPT-5.5 is gone from Codex for ChatGPT sign-in users as of October 14, 2026 at noon PDT (19:00 UTC), so any session still selecting it stops working.
  • API-key sessions and the OpenAI API are untouched, which gives developers a way to keep GPT-5.5 where they authenticate with their own key.
  • GPT-6.1 Sol (gpt-6.1-sol) is the suggested replacement, offering near-Astra performance at a lower cost than Astra.
  • Hardcoded model IDs are the main risk: workspace defaults, saved settings, managed configs, custom agents, scheduled tasks and scripts all need review.
  • Changing a default does not grant access, because GPT-6.1 Sol availability varies by plan, client and workspace settings.
  • The retirement follows a fast model cadence: GPT-6 Sol and Luna arrived on September 22, GPT-6.1 Sol on September 29, and Ultrafast mode on October 8, so pinned model names age quickly.

What Changed

OpenAI retired GPT-5.5 in Codex for people who sign in with a ChatGPT account. The removal took effect on October 14, 2026, at noon PDT (19:00 UTC). From that point, GPT-5.5 can no longer be selected in Codex sessions that use ChatGPT sign-in.

Who Is Affected and Who Is Not

The retirement applies only to Codex sessions authenticated through ChatGPT. Sessions that use an API key, and the OpenAI API itself, are not affected. Developers who run Codex against their own API key can keep using GPT-5.5 there.

The Suggested Replacement

OpenAI points users to GPT-6.1 Sol (gpt-6.1-sol) wherever it is available for their plan and client. GPT-6.1 Sol arrived in Codex and ChatGPT Work on September 29, 2026. It offers near-Astra performance on complex work at a lower cost than Astra, and it is suited to repeated, long-running work across code, apps and documents. Availability still depends on plan, client and workspace settings, so a default change does not by itself give every person access to the new model.

What Teams Should Update

Anything that pins GPT-5.5 by name can break or fall back after the cutoff. OpenAI specifically calls out these places to review:

  • Workspace defaults and saved model settings
  • Managed configurations rolled out to a team
  • Custom agents
  • Scheduled tasks
  • Scripts that pass a model ID

Workspace owners should confirm that the people on their team can actually use GPT-6.1 Sol in the apps they rely on before switching a default.