GPT-5.1 changelog

Every change to GPT-5.1 that Modelpeers has recorded, newest first, each with the source it came from. The record starts Oct 1, 2026.

All (2)Retiring (2)

October 2026

GPT-5.4, GPT-5.4 mini, GPT-5.4 nano

8 products from OpenAI and Perplexity AI

Retired1w

Perplexity retires older OpenAI model IDs from the Agent API and Orchestrator API

The changelog scheduled seven older OpenAI model IDs to retire on October 24, 2026 at 00:00 UTC. After the cutoff the IDs are no longer accepted or returned by model-list endpoints.

Before

openai/gpt-5.4, gpt-5.4-mini, gpt-5.4-nano, gpt-5.2, gpt-5.1, gpt-5 and gpt-5-mini accepted

After

These model IDs are no longer accepted

Who is affected:: Developers who select these OpenAI models directly or in fallback chains in the Agent API or Orchestrator API.
Action needed:: Switch direct model selections and fallback chains to a current OpenAI model such as openai/gpt-6-luna or openai/gpt-6-sol.

GPT-5.3-Codex, GPT-5.1 and GPT-5.4 nano

3 models from OpenAI

RetiringOct 1, 2026

GPT-5.3-Codex, GPT-5.1 and GPT-5.4 nano to shut down April 1, 2027

gpt-5.3-codex and gpt-5.1 will be removed on April 1, 2027 with gpt-6-sol as the replacement. gpt-5.4-nano moves to gpt-6-luna.

Takes effect Apr 1, 2027 · in 151 days

Who is affected:: Apps calling these models.
Action needed:: Migrate before April 1, 2027.

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