GitHub Copilot removes six models on 19 October, including GPT-5.5 and Gemini 3.7 Flash

GitHub Copilot removes six models on 19 October, including GPT-5.5 and Gemini 3.7 Flash

22 September 2026 — GitHub will deprecate six models across every GitHub Copilot experience on 19 October 2026: Copilot Chat, inline edits, ask and agent modes, and code completion. The notice was published on the GitHub Changelog on 18 September.

What goes, and what replaces it

GitHub names a suggested alternative for each model:

• GPT-5.5 and GPT-5.4 are replaced by GPT-5.6 Sol.
• GPT-5.4 mini and GPT-5 mini are replaced by GPT-5.6 Luna.
• Gemini 3.7 Flash is replaced by Gemini 3.8 Flash.
• Grok 4.5 is replaced by Grok 4.6.

All six share the same date. GitHub says no action is needed to remove them once they are deprecated.

Whether the replacements appear on their own

That depends on a setting most teams have never looked at. Under default model enablement, the suggested alternatives are switched on automatically for Copilot Business and Copilot Enterprise customers. That changes if an administrator has turned off the global default, or has explicitly disabled one of the replacement models. In those organisations the replacement stays off until someone enables it in the model policies in Copilot settings. Until then, users who relied on a retired model will find nothing in its place in the model selector.

What to do before 19 October

• Check the default. In Copilot settings, confirm whether the global default for new models is on. If it is off, enable GPT-5.6 Sol, GPT-5.6 Luna, Gemini 3.8 Flash and Grok 4.6 deliberately, or decide which of them your organisation will allow.
• Find the pinned model names. Agent configurations, scripts, editor settings and internal documentation that name one of the six models will stop working on the day. Search for the names now, while there is a month to change them.
• Tell people what changes. A developer who chose GPT-5 mini for fast completions will be moved to a different model with different behaviour. A short note beats a support queue.
• Ask about cost if it matters. The notice does not say whether each replacement uses Copilot's premium allowance at the same rate as the model it replaces. If your organisation budgets by model, get the answer from your account team before the switch rather than on the next invoice.

GitHub Enterprise customers with questions are directed to their account team. The notice links to GitHub's list of supported models, which is the page to check if a further date moves.

Sources

• GitHub Changelog, "Upcoming deprecation of selected GitHub Copilot models in mid-October" — 18 September 2026