---
title: "GitHub Copilot Retires Six Models on September 1 — Here's the Migration List"
date: 2026-08-24
tags: ["github-copilot","claude","gemini","model-deprecation","developer-tools"]
categories: ["AI Tools","Industry"]
summary: "On September 1, GitHub Copilot drops Gemini 3.1 Pro, Claude Opus 4.5, Opus 4.6, Sonnet 4.5, Sonnet 4.6, and Raptor Mini from every Copilot surface. Individual annual-plan subscribers get a one-model carve-out; everyone else has one week left to update their configs."
---


![GitHub Copilot Retires Six Models on September 1 — Here's the Migration List](/images/github-copilot-september-2026-model-deprecations.png)

GitHub confirmed, via its own changelog, that six models are being pulled from GitHub Copilot on **September 1, 2026** — across Chat, coding agent, code review, and every other Copilot surface. This is one of the largest single deprecation waves Copilot has run, and it lands with exactly one week of runway from today. If your team has model pins, org-level policies, or CI configs referencing any of these, this is the week to fix that.

## The list, straight from GitHub's changelog

Per [github.blog's official changelog post](https://github.blog/changelog/2026-07-31-upcoming-august-2026-model-deprecations-in-github-copilot/), the models retiring September 1 and GitHub's suggested replacements are:

| Deprecated model | GitHub's suggested replacement |
|---|---|
| Gemini 3.1 Pro | Gemini 3.6 Flash |
| Claude Opus 4.5 | Claude Opus 4.7, 4.8, or 5 |
| Claude Opus 4.6 | Claude Opus 4.7, 4.8, or 5 |
| Claude Sonnet 4.5 | Claude Sonnet 5 |
| Claude Sonnet 4.6 | Claude Sonnet 5 |
| Raptor Mini | MAI-Code-1-Flash |

There's one carve-out: "Claude Sonnet 4.6 will remain available to individual GitHub Copilot subscribers on annual plans so they retain a Sonnet offering." Everyone else — monthly individual plans, Business, Enterprise — loses all six on the same day, no exceptions. GitHub's guidance is blunt: "update your workflows and integrations to use the supported model before these dates," and pointedly, "no action is required to remove the models once they have been deprecated" — meaning any workflow still pointed at a retired model doesn't degrade gracefully, it just stops working.

## Why four of six are Anthropic models

Look closely at that table and a pattern jumps out: four of the six retirements are Claude models, and all four are being replaced by Claude Sonnet 5 or the Opus 4.7/4.8/5 line. That's not GitHub abandoning Anthropic — it's the opposite. Copilot is retiring *older* Claude generations because Anthropic's own release cadence made them obsolete. Opus 4.5 and 4.6 predate Opus 4.7's implicit-need testing and multi-agent coordination work; Sonnet 4.5 and 4.6 predate Sonnet 5's native 1M context and new tokenizer. GitHub is just following Anthropic's own model lifecycle, one release cycle behind.

Gemini 3.1 Pro's retirement fits a wider pattern too: Google has struggled to ship Gemini 3.5 Pro on schedule all year (still not GA as of this writing, months past its original target), leaving Gemini 3.6 Flash — a speed-tier model, not a flagship successor — as Copilot's actual recommended replacement. That's a downgrade in everything but name for anyone doing heavy agentic coding on Gemini through Copilot.

## The real story: Copilot's model-zoo tax

This is where the editorial angle matters. GitHub Copilot's pitch has always been model breadth — pick from a dozen-plus models across four vendors, mix and match per task. It's a reasonable pitch for exploration. But breadth has a maintenance cost that Copilot keeps passing straight to its users: six models retiring on one day, an annual-plan-only carve-out that Business and Enterprise customers don't get, and a hard cutover with no fallback behavior.

Compare that to what shipped on the Claude Code side this same week (see our [v2.1.234-241 roundup](/2026/08/claude-code-v2-1-234-241-week-in-review/)): Anthropic added `ANTHROPIC_DEFAULT_MODEL`, an environment variable specifically designed so a fleet of sessions or CI runners can standardize on a default model *without* every workflow needing a hardcoded pin that breaks on the next deprecation. When Claude Code's own default model changes — as it did automatically when Opus 5 became default in July — existing sessions don't halt, they just get better. There's no calendar-deadline scramble because there's one vendor, one coherent model lineage, and the harness is built around that model improving out from under you gracefully.

Copilot's model picker is genuinely useful for comparing outputs across vendors. But "genuinely useful for comparison" and "reliable production infrastructure" are different properties, and this deprecation wave is a reminder of which one you're actually signing up for when six models can vanish from your CI pipeline on a single Tuesday with a one-line changelog notice as your only warning.

## What to actually do this week

If you're running Copilot in any automated context — coding agent workflows, custom chat participants with a pinned model, org-level Copilot policies restricting model choice — audit for these six names now:

1. **Search your `.github/copilot` configs and any CI YAML** for explicit references to `gemini-3.1-pro`, `claude-opus-4.5`, `claude-opus-4.6`, `claude-sonnet-4.5`, `claude-sonnet-4.6`, or `raptor-mini`.
2. **Enterprise/Business admins**: check your org's model-access policy in Copilot settings — if any of these six are explicitly enabled or required, swap them for the suggested replacements before September 1, not after.
3. **Individual annual-plan subscribers on Sonnet 4.6**: you're exempt, but budget for this being a temporary reprieve — GitHub didn't commit to how long the carve-out lasts.
4. **Everyone else on Sonnet 4.5/4.6**: move to Claude Sonnet 5 directly rather than waiting — per our own model tracking, Sonnet 5 beats Opus 4.8 on Terminal-Bench 2.1 (80.4% vs 74.6%) at a fraction of the cost, so this isn't a downgrade dressed up as forced migration.

**Sources**: [GitHub Copilot changelog, "Upcoming August 2026 model deprecations"](https://github.blog/changelog/2026-07-31-upcoming-august-2026-model-deprecations-in-github-copilot/) (primary, fetched directly for the full model list, dates, and exact quotes above).