On May 30th, 2026, Microsoft moved Copilot Studio agents from Claude Sonnet 4.5 to 4.6. Configurations and integrations will carry over fine, but the quality and tone of the responses might shift. If you have business-critical agents still on Sonnet 4.5, you should test them against 4.6 (or Opus 4.6) before May 30th to ensure they still meet your standards.
We recommend identifying your high-impact agents and running a few comparison tests. If things look off, you can defer the switch for 30 days using the “retired models” toggle in the admin center, but this is only a short-term safety net. Model migrations like this are where Copilot Studio agents quietly drift.
We help teams stand up regression testing to ensure every update is a step forward, not a setback.
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About the Author: Luis Palacios
