GitHub Copilot sets October 19 deadline for six model migrations

GitHub will deprecate six models across GitHub Copilot on October 19, 2026. The change reaches Copilot Chat, inline edits, Ask mode, agent mode, and code completions, giving teams with pinned model preferences a clear migration deadline.

The six Copilot models leaving on October 19

GitHub’s notice names these models and replacements:

The mapping is GitHub’s recommendation, so test important workloads before switching.

What changes for enterprise administrators

GitHub says suggested alternatives are automatically enabled for Copilot Business and Enterprise customers when default model enablement is active. Administrators who disabled the global default or a replacement must review model policies in Copilot settings.

Users will see enabled replacements in the Copilot Chat model selector where supported. Repositories, extensions, scripts, evaluations, and team guidance may still refer to old names.

Check pinned workflows before the cutoff

Check three inventories:

1. Defaults: find policies that select a deprecated model or hide replacements.
2. Automation: search configuration files, wrappers, evaluations, and runbooks for the six names.
3. Baselines: rerun representative coding, review, and agent tasks against the alternatives.

Keep model selection behind a configuration layer and record the replacement, date, benchmark set, and rollback decision. LinkLoot’s AI workflow automation guide covers that pattern.

Evidence and next milestone

The operative date is October 19, 2026. GitHub has not announced a grace period in the deprecation notice, so organizations should treat that date as the point by which their policies and tests need to be ready.

GitHub’s changelog is the primary source for the retirement list and deadline. xAI’s release notes independently confirm that Grok 4.6—the suggested replacement for Grok 4.5—is available through its developer API.