GitHub Copilot: Six Models Set to Retire October 19

GitHub CopilotSep 18, 2026View original changelog

GitHub announced it will deprecate six models across every GitHub Copilot experience, including Chat, inline edits, ask and agent modes, and code completions, on October 19, 2026. The retiring lineup covers Gemini 3.7 Flash, GPT-5.5, GPT-5.4, GPT-5.4 mini, GPT-5 mini, and Grok 4.5, with GitHub pointing developers to Gemini 3.8 Flash, GPT-5.6 Sol, and GPT-5.6 Luna as replacements. Copilot Business and Enterprise admins who have turned off global default model enablement will need to manually enable the suggested alternatives through their model policies before the cutoff.

Key Takeaways

GitHub Copilot will retire six models on October 19, 2026: Gemini 3.7 Flash, GPT-5.5, GPT-5.4, GPT-5.4 mini, GPT-5 mini, and Grok 4.5.
The deprecation spans every Copilot surface, including Chat, inline edits, ask and agent modes, and code completions, not just one product area.
Gemini 3.8 Flash replaces the retiring Gemini Flash model, while GPT-5.6 Sol and GPT-5.6 Luna absorb the retiring GPT-5.5/5.4 and mini-tier models respectively.
Grok 4.5 is being replaced by Grok 4.6, continuing GitHub's pattern of retiring a model shortly after its successor ships.
Admins who disabled global default model enablement must manually turn on replacement models through Copilot's model policies before the cutoff, or users will lose access without a fallback.
GitHub says no action is required to remove the old models after October 19; they simply stop being selectable once the date passes.

Six Models Retiring on October 19

GitHub will deprecate six GitHub Copilot models on October 19, 2026, across all Copilot surfaces, including Copilot Chat, inline edits, ask and agent modes, and code completions. The retiring models and their suggested alternatives are as follows: Gemini 3.7 Flash moves to Gemini 3.8 Flash; GPT-5.5 and GPT-5.4 both move to GPT-5.6 Sol; GPT-5.4 mini and GPT-5 mini both move to GPT-5.6 Luna; and Grok 4.5 moves to Grok 4.6.

What Developers and Admins Need to Do

GitHub is asking developers to update workflows and integrations that reference the retiring models before the October 19 cutoff. Under default model enablement, the suggested alternatives are automatically turned on for GitHub Copilot Enterprise and GitHub Copilot Business customers, unless an administrator has disabled the global default or explicitly turned off a specific model. Administrators in that situation can enable access to the alternative models through their model policies in Copilot settings. Once a replacement model is enabled, it appears in the Copilot Chat model selector across supported GitHub Copilot experiences.

No action is required to remove the deprecated models once October 19 arrives; they will simply stop being available. GitHub Enterprise customers with questions about the transition are encouraged to contact their account team, and GitHub points developers to its documentation on supported models for further detail.