GitHub deprecates the GPT-5.1-Codex family across Copilot and points teams to GPT-5.3-Codex

In an April 3, 2026 X post, GitHub Changelog said the GPT-5.1-Codex model family had been deprecated across all GitHub Copilot experiences effective April 1. The linked changelog entry says the change spans Copilot Chat, inline edits, ask and agent modes, and code completions. GitHub's direct recommendation is straightforward: move to supported models, with GPT-5.3-Codex presented as the alternative.

The operational detail matters for enterprise teams. GitHub says workflows and integrations should be updated, and Copilot Enterprise administrators may need to enable alternative models through model policies in Copilot settings. Administrators can verify availability by checking their individual Copilot settings and confirming the relevant policy is enabled. Once that is done, the replacement model should appear in the Copilot Chat model selector in VS Code and on github.com. GitHub also notes that no cleanup action is required to remove the deprecated models themselves.

GitHub is tightening the model lifecycle around Copilot governance

This is more than a product catalog update. As Copilot becomes a policy-managed surface inside larger organizations, model turnover affects approvals, integrations, and internal support processes. GitHub is effectively telling enterprise customers that the Codex stack will keep moving and that staying current requires model governance, not just developer preference. The timing is also notable because GitHub is simultaneously elevating GPT-5.3-Codex as the successor path, including a separate long-term-support commitment for business and enterprise plans. Sources: the X post and GitHub's changelog.