OpenAI Codex changelog

Every change to OpenAI Codex that Modelpeers has recorded, newest first, each with the source it came from. The record starts Oct 6, 2025.

All (36)Releases (13)Retiring (7)Breaking changes (2)Prices/limits (7)Quality (5)Benchmarks (2)

September 2026

OpenAI Codex and GPT-6.1 Sol

2 products from OpenAI

Default changeSep 29, 2026

GPT-6.1 Sol becomes the default model in the Codex CLI catalog

Codex CLI 0.159.1 added GPT-6.1 Sol as the default model in the bundled catalog and the Amazon Bedrock Mantle and Runtime catalogs.

After

GPT-6.1 Sol

Who is affected:: Codex CLI users who have not pinned a model.
What to do:: Pin a model in your Codex config if you need the previous default.

OpenAI Codex

Agent at OpenAI

Breaking changeSep 5, 2026

codex mcp-server command removed

The codex mcp-server command and the standalone codex-mcp-server binary were removed after deprecation on August 24, 2026. Connecting to external MCP servers through codex mcp still works.

Who is affected:: Integrations that launch Codex as an MCP server.
Action needed:: Move integrations to the Codex app server before upgrading Codex.

14 incidents are listed on the OpenAI Codex page. Get this changelog in a feed reader with the RSS feed.