GitHub Retires Six Copilot Models: Replacement Map and Enterprise Policy Checks

The replacement map​

GitHub's September 18 retirement notice (deprecation effective October 19) lists these suggested alternatives:

The deprecation date for all six is 2026-10-19. GitHub says the deprecations were first announced on September 18.

The successors come from the single September 18 notice​

GitHub published one retirement notice, on September 18, and has not changed it. The successors it names are:

• GPT-5.5 and GPT-5.4 pointed to GPT-5.6 Sol.
• GPT-5.4 mini and GPT-5 mini pointed to GPT-5.6 Luna.
• Grok 4.5 pointed to Grok 4.6.

Third-party coverage of the retirement, such as the Tech Insider piece, repeats the September names, which remain the current ones. The Gemini mapping is unchanged.

Before you rewrite any configuration, confirm that the exact model you pick appears in your own account's model selector or policy list.

What administrators need to do​

GitHub's retirement notice says Copilot Enterprise administrators may need to enable the alternative models through model policies in Copilot settings. To check, look at your Copilot settings and confirm the policy is enabled for the specific model. Once it is enabled, the model shows up in the Copilot Chat model selector in VS Code and on github.com. GitHub says no action is needed to remove the deprecated models. Enterprise customers with questions are pointed to their account manager.

The September 18 notice — GitHub's only retirement notice for this deprecation — also states the following detail. Under default model enablement, the suggested alternatives are automatically enabled for Copilot Enterprise and Copilot Business customers. That doesn't apply if an administrator has turned off the global default or explicitly disabled the model. If the global default is off, administrators have to enable the alternatives themselves through model policies. This is the earlier announcement's guidance, not a new October instruction.

One reported claim doesn't line up with GitHub's own text. Tech Insider says Business and Enterprise customers were switched automatically, with no toggle to flip. GitHub's notice instead says administrators may need to enable alternatives, and the September post describes the auto-enable as conditional. I'd trust GitHub's wording over that summary.

A practical checklist​

GitHub's notices don't describe an API migration. They also don't say that existing configurations switch models automatically. These checks are my own suggestions, drawn from general practice and from the model-pinning scenarios in the Creuto write-up:

• Search repositories, shared editor settings and CI configuration for the six retired model names. The Creuto write-up suggests a quick grep does most of the job.
• Review any organization allowlist of permitted models. Entries for retired models are now stale.
• Confirm the policy for each replacement is enabled for the relevant users.
• Test the replacement in the Copilot surface your team uses. Don't assume it behaves like the model it replaces. Two pairs of retired models collapse into one replacement each, which changes behavior rather than just bumping a version.

A related API for managing model policies​

GitHub also announced on October 19 that REST API GET and PATCH endpoints for Copilot model policies are generally available at the organization level only:

• Organization: /orgs/{org}/copilot/model-policies

GitHub documents no enterprise, enterprise-team, or enterprise-app model-policy endpoints; model policies set at the enterprise level can still delegate control to organizations. The announcement doesn't tie these endpoints to the deprecation. The settings check above is the route GitHub actually states.

What GitHub doesn't say​

The retirement notice leaves several questions open:

• It gives no reason for the retirements.
• It gives no exact cutoff time or time zone.
• It doesn't say whether every client stops offering the models at the same moment.
• It lists no client version requirements.

Another model change is already on the calendar. A DEV Community write-up says that on November 16, 2026, Claude Opus 4.8, Claude Opus 5 and GPT-5.6 Terra leave the Copilot model picker, citing GitHub's October 15 changelog entry. (GitHub's entry excepts Claude Opus 4.8 for individual GitHub Copilot subscribers on annual plans.) If you are auditing hard-coded model names now, check for those too. Otherwise you'll be doing the same audit again in four weeks.

Correction (October 19, 2026): The replacement-model table now uses GitHub's September 18 retirement notice, the only notice GitHub published for the October 19 deprecation — successors are GPT-5.6 Sol, GPT-5.6 Luna, Grok 4.6 and Gemini 3.8 Flash; GitHub's notice covers "all" Copilot experiences, not "most". The model-policy REST API section was corrected: GitHub documents the GET/PATCH endpoints at the organization level only (/orgs/{org}/copilot/model-policies). The November 16 note now includes GitHub's exception keeping Claude Opus 4.8 for individual Copilot subscribers on annual plans.