Gemini 2.5 Pro and Gemini 3 Flash Deprecated in GitHub Copilot: What to Switch To

GitHub deprecated two Google models across every Copilot experience on July 31, 2026: Gemini 2.5 Pro and Gemini 3 Flash. The change lands in Copilot Chat, inline edits, ask and agent modes, and code completions, and it is effective immediately. The official changelog entry lists Gemini 3.1 Pro (currently in public preview) as the replacement for Gemini 2.5 Pro, and Gemini 3.6 Flash as the replacement for Gemini 3 Flash.

This is the second model-related removal from GitHub this week: GitHub Models was fully retired on July 30. If your team pins models in Copilot, today is a good day to check which ones you are actually calling.

What actually changed#

The deprecation applies to all Copilot plans and surfaces. The models no longer appear in the model selector, and requests that reference them do not route. There is no grandfathering period and no opt-out: "No action is required to remove the deprecated models," the changelog says, because the removal is server-side.

The one place where action is required is Copilot Enterprise. The changelog notes that enterprise administrators may need to enable the replacement models through their model policies in Copilot settings. Gemini 3.1 Pro is a preview model, and preview models are commonly disabled by default in enterprise policies. If a team wants Gemini 3.1 Pro, an admin has to flip that policy on before the model shows up in the VS Code or github.com model selector.

What survives, per the current Copilot supported models documentation, is a Google lineup of three models: Gemini 3.6 Flash and Gemini 3.5 Flash at GA status, plus Gemini 3.1 Pro in public preview. Gemini 2.5 Pro and Gemini 3 Flash are gone from the list entirely.

Why Gemini 3.6 Flash is a fair upgrade#

Google launched Gemini 3.6 Flash on July 21 as a direct efficiency play: 17% fewer output tokens than Gemini 3.5 Flash per task at $1.50 per million input tokens and $7.50 per million output tokens. On DeepSWE it scores 49% versus 37% for Gemini 3.5 Flash, and on MLE Bench it hits 63.9% versus 49.7%. For Copilot users the token efficiency matters twice: fewer output tokens means faster completions and, on usage-based billing plans, fewer premium requests consumed.

The interesting side note is that Gemini 3.5 Flash-Lite, launched the same day at $0.30 per million input and $2.50 per million output tokens, already outscored Gemini 3 Flash on SWE-Bench Pro (54.2% versus 49.6%) and OSWorld-Verified (74.0% versus 65.1%). In other words, the model being removed was already beaten by the cheap tier of the current line. The deprecation is not a downgrade for most workloads.

What this signals about Copilot's model strategy#

Reading the July changes together, GitHub is consolidating hard. GitHub Models retirement removes the neutral API surface that let anyone call any provider's model with a GitHub token. The new enterprise model policy targeting in public preview gives admins fine-grained control over which models their teams can see. And now the two oldest Gemini entries in the Copilot catalog are gone.

The throughline: Copilot is moving from a marketplace of many models to a curated, policy-managed set. For individual developers the practical cost is low, mostly a model-selector change. For teams that built scripts, prompts, or automation around a specific model string, this is a reminder that model names in Copilot are now moving targets. The GitHub Models retirement post covers the API side; this change is the same churn inside the editor.

How to migrate#

The concrete checklist, based on the changelog and the supported-models documentation:

1. Open the model selector in VS Code and in Copilot Chat and confirm which Gemini models are actually listed. If you pinned Gemini 2.5 Pro or Gemini 3 Flash, switch to Gemini 3.1 Pro or Gemini 3.6 Flash respectively.
2. If you are on Copilot Enterprise and Gemini 3.1 Pro is not visible, have an admin check the model policy in Copilot settings and enable the preview model. The changelog says verification is via the individual Copilot settings page, and that the model appears in the selector once the policy is enabled.
3. Search your repo for the model strings, including any in configuration files or team documentation, and update anything that instructs the model to use the old names.
4. Run a quick smoke test on your most important assisted workflow with the new model before relying on it. If you automated prompts that depended on Gemini 2.5 Pro's specific behavior, budget a small eval pass.

If you are coming from a broader model access question, the migration checklist in Migrating Off Retired GPT Models in 2026 covers the general playbook: read the retirement table, map old names to new ones, eval before you switch, and keep a provider fallback. The pattern is identical here, just with a shorter runway.

Continue Reading#

• GitHub Models Is Retired: What to Use for Model Access Now - the API-side retirement that landed one day earlier
• Enterprise Teams Model Policy Targeting in Public Preview - how admins control which models a team can use
• Migrating Off Retired GPT Models in 2026 - the general model-deprecation migration playbook
• Gemini 3.5 Pro Developer Guide 2026 - what the current Gemini line offers and how to use it
• Claude Fable 5 vs Gemini 3.1 Pro - a head-to-head on the model GitHub suggests for Gemini 2.5 Pro users
• Kimi K3 Is GA in GitHub Copilot: Pricing, Rollout, and What It Means for Model Choice

Sources#

• GitHub Changelog: Gemini 2.5 Pro and Gemini 3 Flash deprecated
• GitHub Docs: Supported AI models in GitHub Copilot
• Google: Introducing Gemini 3.6 Flash, 3.5 Flash-Lite, and 3.5 Flash Cyber