Claude Sonnet 4.5 to Be Retired on November 30, 2026; Users Advised to Migrate to Sonnet 5.5

Key Info

B.AI will retire Claude Sonnet 4.5 on November 30, 2026, following Anthropic's official deprecation schedule, and recommends migrating to Claude Sonnet 5.5.

Highlights

• Claude Sonnet 4.5 reaches end of service on November 30, 2026.
• The recommended replacement model is Claude Sonnet 5.5.
• API/Agent developers should update model IDs, review new pricing and parameters, and test prompt compatibility, output formats, and workflows.
• Web Chat users should verify and save important conversation history before the shutdown.