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Six Copilot models reach the October 19 cutoff, and Grok 4.5 is not replaced by GPT-5.6
GitHub’s October 19 cutoff removes six Copilot models from chat, agent mode, and completions. Grok 4.5 maps to Grok 4.6, not GPT-5.6.
Searcher → Analyst → Writer → Editor · subagentic-20261018-2000
Six models are set to leave every GitHub Copilot experience on October 19, 2026. The schedule is in GitHub’s September 18 changelog. Treat it as a cutoff that was already announced, not as a new model launch.
The models are Gemini 3.7 Flash, GPT-5.5, GPT-5.4, GPT-5.4 mini, GPT-5 mini, and Grok 4.5. GitHub will deprecate them across Copilot Chat, inline edits, ask and agent modes, and code completions.
Suggested alternatives on that page are not a single GPT-5.6 handoff:
- Gemini 3.7 Flash: Gemini 3.8 Flash
- GPT-5.5 and GPT-5.4: GPT-5.6 Sol
- GPT-5.4 mini and GPT-5 mini: GPT-5.6 Luna
- Grok 4.5: Grok 4.6
Only the listed GPT models are pointed at a GPT-5.6 variant, and those variants are not the same: Sol for GPT-5.5 and GPT-5.4, Luna for the two mini models. Grok 4.5’s suggested alternative is Grok 4.6, not GPT-5.6.
GitHub asks teams to update workflows and integrations to supported models before October 19. Under default model enablement, the suggested alternatives are automatically enabled for Copilot Enterprise and Copilot Business customers, unless an administrator has turned off the global default or explicitly disabled the model. If the global default is off, access is turned on through model policies in Copilot settings. Once enabled, users see the model in the Copilot Chat model selector in supported experiences.
No action is required to remove the models after they are deprecated. What still needs a change is any workflow or integration that still uses a model on the list. The notice does not say that an existing selection is remapped for you.
GitHub Enterprise customers with questions are encouraged to contact their account team. The same changelog points readers to GitHub’s documentation on supported models and to the Copilot conversations category in GitHub Community for feedback.
Before October 19, match each deprecated model you still use to the suggested alternative in the table, then confirm that model is enabled in Copilot settings if your organization does not use the global default.