What happened
GitHub says it deprecated six models across most GitHub Copilot experiences, including Copilot Chat, inline edits, ask and agent modes, and code completions. The affected models are Gemini 3.1 Pro, Claude Opus 4.5, Claude Opus 4.6, Claude Sonnet 4.5, Claude Sonnet 4.6, and Raptor Mini. The listed deprecation date for each model is September 1, 2026.
GitHub’s changelog says that, as of September 1, 2026, it deprecated six models across most GitHub Copilot experiences. The affected surfaces named in the notice are Copilot Chat, inline edits, ask mode, agent mode, and code completions. This makes the change broader than the removal of a model from a single interface: the notice describes a change to several ways developers use Copilot for coding assistance and task execution.
The deprecated models listed by GitHub are Gemini 3.1 Pro; Claude Opus 4.5; Claude Opus 4.6; Claude Sonnet 4.5; Claude Sonnet 4.6; and Raptor Mini. GitHub pairs each model with a suggested alternative. Gemini 3.1 Pro is paired with Gemini 3.7 Flash; the two Claude Opus models are paired with Claude Opus 4.7, Claude Opus 4.8, or Claude Opus 5; Claude Sonnet 4.5 and 4.6 are paired with Claude Sonnet 5; and Raptor Mini is paired with MAI-Code-1.1-Flash.
The notice includes one exception: Claude Sonnet 4.6 remains available to individual GitHub Copilot subscribers on annual plans. GitHub does not explain in the source whether that exception applies to every Copilot experience or only to the availability of the model for that subscriber group. It also does not specify whether the alternatives are automatically substituted in existing workflows or whether users must select them manually.
GitHub says no action is required to remove the deprecated models. It nevertheless asks users to update workflows and integrations to supported models. The notice says Copilot Enterprise administrators may need to enable alternative models through model policies in Copilot settings. The page displays a visible label reading “Retired August 31, 2026,” while the notice says “as of today, September 1, 2026” and lists September 1 as the deprecation date. The source does not resolve that apparent timing discrepancy.
Why it matters
The change can require developers and organizations to revise Copilot workflows, integrations, model policies, or model selections. GitHub provides suggested replacements, but the source does not establish whether those alternatives behave equivalently, have the same cost or availability, or preserve existing workflow results.
Model availability is part of how Copilot behaves in practical development workflows. Because GitHub identifies Chat, inline editing, ask mode, agent mode, and code completion as affected experiences, teams that selected one of the deprecated models may need to review more than a single preference. The direct, source-grounded consequence is a change in which AI systems can be used through those Copilot functions; the source does not quantify how many users, repositories, or organizations are affected.
For enterprise users, the change also introduces an administrative dependency. GitHub says administrators may need to enable alternative models through model policies before those models appear in the Copilot Chat model selector in VS Code and on github.com. That means a suggested replacement is not necessarily available automatically to every organization. The notice gives administrators a verification path—checking individual Copilot settings and confirming that the relevant policy is enabled—but does not describe how policies are configured across larger organizations.
The replacement list provides direction but not an equivalence assessment. GitHub does not publish performance comparisons, compatibility information, pricing information, rate limits, context limits, or migration guidance in this notice. It also does not say whether a workflow built around a deprecated model will produce materially different code, explanations, edits, or agent behavior after moving to a suggested alternative. Those unknowns matter to developers who rely on consistent outputs or to organizations that have evaluated models for particular tasks.
The notice is therefore a concrete product change, but its practical severity will vary by user. Someone who did not select the affected models may see no change, while a user or enterprise integration that explicitly depended on one may need to modify settings or code. The source does not provide usage figures, evidence of service disruption, or user reactions, so the public record here supports reporting the availability change but not claims about its scale or effects on software quality.
What to watch next
Enterprise administrators should verify that replacement models are enabled through Copilot model policies. Users should check whether their preferred alternatives appear in Copilot settings and model selectors. GitHub also says Claude Sonnet 4.6 remains available to individual subscribers on annual plans, while the page’s visible retirement label says August 31 even though the notice states September 1, leaving the exact timing context unclear.
The immediate issue for enterprise administrators is whether the suggested alternatives are enabled under their organization’s Copilot model policies. GitHub says administrators can confirm availability through individual Copilot settings and then see enabled models in the Copilot Chat model selector in VS Code and on github.com. The source does not say whether policy changes propagate immediately or whether additional integration changes are required.
Developers should watch for differences between the deprecated model and the selected replacement in the Copilot experiences they use. GitHub names code completions, inline edits, Chat, ask mode, and agent mode, but does not describe model-by-model behavior in those surfaces. Any assessment of changed quality, latency, cost, or reliability would require evidence not included in this notice.
The annual-plan exception for individual subscribers is another point requiring clarification. GitHub specifically says Claude Sonnet 4.6 is still available to individual subscribers on annual plans, but it does not state how that exception interacts with the broader deprecation notice or whether availability differs across Copilot products and interfaces. Users in that group should verify the model’s actual presence in their own settings rather than infer universal access from the exception.
The timing language should also be monitored. The page’s visible status says “Retired August 31, 2026,” while the body describes the deprecation as taking effect September 1. GitHub’s notice lists September 1 as the deprecation date for all six models, but the source does not explain whether August 31 refers to the changelog status, publication timing, or an earlier retirement step. GitHub Enterprise customers with questions are directed to their account managers.