GitHub removes Claude Opus 4.8, Claude Opus 5 and GPT-5.6 Terra from Copilot on 16 November 2026. If you are on any of those, you pick a replacement in the next four weeks. These are the two defaults.
The migration map
| Retiring | GitHub's suggested replacement |
|---|
| Claude Opus 4.8 | Claude Opus 5.5 (stays for individual annual subscribers) |
| Claude Opus 5 | Claude Opus 5.5 |
| GPT-5.6 Terra | GPT-6.1 Sol or GPT-6 Luna |
Pick by what broke, not by benchmark
A migration is the wrong moment to switch families on general reputation. The useful question is narrower: which of the two annoyed you less on your own codebase.
Stay on Opus if your work is large-diff refactors, multi-file reasoning and anything where following an existing convention matters more than raw generation speed. The Opus line has been the stronger choice for holding a long codebase context without drifting.
Move to GPT-6.1 Sol if you were on Terra and liked it. Within-family migration preserves the prompt habits and failure modes you already know, and most teams underrate how much time that saves. GPT-6 Luna is the lighter option where latency beats depth.
Do this before 16 November
- Grep every repo for pinned model names — Copilot config, agent definitions, CI steps
- Decide whether a pinned name that silently falls back to a default is acceptable; usually it is not, because you lose a week to confusing output rather than getting a clean error
- Check whether anything depends on Opus 5 specifically. It remains on Anthropic's own API past this date, so the fix may be moving the call rather than changing the model
- Run your five hardest real tasks against both candidates in the same week, before the deadline forces the choice
FAQ
Is Claude Opus 5 being discontinued?
No. This is a GitHub Copilot availability decision. Opus 5 remains available through Anthropic's API well beyond 16 November 2026.
I am on an individual annual plan. Do I lose anything?
Opus 4.8 stays available to you. Opus 5 and GPT-5.6 Terra go for everyone.
What happens on 16 November if I do nothing?
GitHub has not published the exact failure behaviour. Plan for a fallback to a default model rather than an error, which is the outcome that costs you the most time to notice.
Related: Copilot retires three models on 16 November