This article is a technical explanation and implementation example generated using AI. While the code and procedures presented are based on primary sources, they have not been verified on actual hardware by the author. Behavior may vary depending on the environment and version.
When using GitHub Copilot, we outline key points for safely preparing for the migration and discontinuation of available AI models. This article explains the changes, alternative models, and configuration policies for administrators described in the primary sources.
Objective
The purpose of this article is to understand the impact on development workflows and integrations due to the scheduled retirement (deprecation) of certain GitHub Copilot models in mid-October 2026, and to safely plan the necessary actions. Based on primary sources, we review the affected models, recommended alternative models, and configuration management mechanisms.
Prerequisites and Cautions
The content covered in this article is based on the primary source published in the GitHub Changelog on September 18, 2026.
The author has not verified the behavior in an actual hardware environment. Verification tasks using PowerShell, APIs, or CLI in a Windows environment are marked as [Scheduled for verification in Windows environment] and [Before actual device verification].
Organizations and development teams must review their workflows and integrations before the retirement date of the target models.
Deprecation Schedule for Target Models and Alternative Models
According to primary sources, specific models will be deprecated on October 19, 2026, across all GitHub Copilot experiences (including Copilot Chat, inline editing, ask mode, agent mode, and code completion).
The mapping between the deprecated models and their respective recommended alternative models is as follows.
Gemini 3.7 Flash: Deprecated on October 19, 2026; recommended alternative model is
Gemini 3.8 FlashGPT-5.5: Deprecated on October 19, 2026; recommended alternative model is
GPT-5.6 SolGPT-5.4: Deprecated on October 19, 2026; recommended alternative model is
GPT-5.6 SolGPT-5.4 mini: Deprecated on October 19, 2026; recommended alternative model is
GPT-5.6 LunaGPT-5 mini: Deprecated on October 19, 2026. The recommended alternative model is
GPT-5.6 LunaGrok 4.5: Deprecated on October 19, 2026. The recommended alternative model is
Grok 4.6
Workflows and integrations using these models are required to be updated to supported models by the deadline.
Administrator Settings and Model Activation Behavior
When default model activation settings are applied, recommended alternative models are automatically enabled for Copilot Enterprise and Copilot Business customers, unless administrators have disabled the global default or individually disabled the models.
If administrators have disabled the global default, access to alternative models can be enabled through the model policies in Copilot settings.
Once enabled, users can select the new model from the Copilot Chat model selector within the corresponding GitHub Copilot experience. Furthermore, cleanup operations after model deprecation are handled automatically, meaning manual deletion actions by users are not required.
Support System for GitHub Enterprise Users
GitHub Enterprise customers with questions or concerns regarding this model deprecation and migration are encouraged to contact their account team for assistance. Additionally, users are advised to refer to GitHub's supported models documentation for details on available models and to share feedback via the GitHub Community.
Limitations
This article is based on publicly available primary source text and is based on research conducted prior to physical device verification regarding actual UI changes and API response formats on GitHub.
Behavior may vary depending on the timing of settings propagation in the actual environment and the application status of policies for each organization.
Conclusion
, official information regarding the deprecation schedule and migration of specific models in GitHub Copilot has been organized. The points and constraints to check before execution are as follows.
Verify the deprecation deadline of October 19, 2026, and check whether any models currently in use are included.
Plan and update the models specified in workflows and integrations to the recommended alternative models.
Understand in advance the configuration status of global defaults and model policies applied by organizational administrators.
Note that the procedures, code, and API output verification in this article are scheduled for confirmation in a Windows environment, and physical device verification results are not included.
