Key Info
B.AI reminded developers and users that Claude Sonnet 4.5 will be retired on November 30, 2026, with 18 days remaining to migrate to the recommended replacement, Claude Sonnet 5.5.
Highlights
- Claude Sonnet 4.5 stops service on November 30, 2026, per Anthropic's deprecation schedule.
- API and agent developers should update model IDs, verify new pricing and parameters, and test prompt compatibility and output formats.
- Web chat users are advised to save important conversation history before the cutoff.
- Migration details are available in the original notice post.