Claude Sonnet 3.5 Retired, Claude Haiku 4.5 Now Powers Copilot Free Experience

.Claude Model Upgrade: Copilot Free Gets Claude Haiku 4.5 As Sonnet 3.5 Departs

Anthropic has announced the deprecation of Claude Sonnet 3.5, effective November 6, 2025, across all GitHub Copilot experiences—including Copilot Chat, inline edits, and agent modes. The move is part of a broader upgrade strategy to deliver more capable and efficient AI models to users on the Free plan.

Replacing Sonnet 3.5 is Claude Haiku 4.5, Anthropic’s fastest model to date, offering near-frontier performance with improved instruction following, faster response times, and better contextual understanding. This transition reflects Anthropic’s commitment to continuous model innovation and safer AI deployment.

Important points:

Model transition 

•   Claude Sonnet 3.5 deprecated on November 6, 2025  
•   Claude Haiku 4.5 now available for Copilot Free users  

Performance upgrades  

•   Haiku 4.5 delivers faster, more intelligent responses  
•   Enhanced instruction following and contextual reasoning  

Developer impact  

•   No action required for Free users  
•   Enterprise admins may need to update model policies  

Sources: Claude Docs, Claude 4.5 Release Notes, GitHub Changelog