Microsoft 365 Copilot: Claude Sonnet 4.5 retiring for Copilot Studio (automatic migration to Claude Sonnet 4.6)

Claude Sonnet 4.5 in Microsoft Copilot Studio will retire by May 30, 2026, with automatic migration to Claude Sonnet 4.6 starting then. An evaluation window from April 30 to May 30, 2026, allows testing and proactive migration. A one-time 30-day deferral is available until June 30, 2026. Starting May 30, Microsoft Copilot Studio agents that are currently configured to use Claude Sonnet 4.5 will be automatically migrated to newer, supported models. This migration aligns Copilot Studio with modern model capabilities, consistent platform support, and long-term reliability. Claude Sonnet 4.5 will be moved to a retired state. When this will happen April 30, 2026: Evaluation window opens. Makers can test and update agents to newer supported models. This evaluation window allows you to test and select the model that best meets your needs before automatic migration occurs. May 30, 2026: Claude Sonnet 4.5 moves to a retired state and phased automatic migration begins. June 30, 2026: Final migration deadline after deferral; all remaining agents are migrated automatically. How this affects your organization Who is affected Admins and makers using Microsoft Copilot Studio Organizations with Copilot Studio agents currently configured to use Claude Sonnet 4.5 What will happen Any agents still using Claude Sonnet 4.5 on May 30, 2026, will be automatically migrated to Claude Sonnet 4.6. From April 30 to May 30, 2026, makers can test and proactively migrate agents to Claude Sonnet 4.6 or another supported model to validate behavior before automatic migration begins. Automatic migration will occur in a phased rollout beginning May 30. Admins can enable a one-time 30-day deferral of automatic migration (until June 30) using the Continue using retired models toggle. After June 30, all remaining agents will be migrated automatically. Agent configurations, flows, integrations, security, compliance, and governance controls remain unchanged. Responses may vary after migration due to differences in model behavior (for example, tone, formatting, or response quality). Usage analytics and reporting will reflect the new model after migration. Agents not using Claude Sonnet 4.5 are not affected. What you can do to prepare We recommend that administrators and makers:  Review Copilot Studio agents […]

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