# claude-sonnet-4-5

Calls to the model claude-sonnet-4-5 on Anthropic stop working on November 30, 2026.

Anthropic deprecated model claude-sonnet-4-5 on September 30, 2026, and will retire it on November 30, 2026. Calls specifying this model will fail after that date. The deprecation affects requests made to api.anthropic.com using model claude-sonnet-4-5.

## The error Anthropic returns once claude-sonnet-4-5 is gone

HTTP 404

```json
{"type":"error","error":{"type":"not_found_error","message":"model: claude-sonnet-4-5"}}
```

## What to use instead

Move to claude-sonnet-5-5, recommended by Anthropic.

- API: Anthropic (api.anthropic.com)
- Model: claude-sonnet-4-5
- Released: September 29, 2025 (models.dev)
- Kind: Model retirement
- Announced: September 30, 2026
- Takes effect: November 30, 2026
- Calls after that day: fail
- Calls it hits: `model claude-sonnet-4-5`
- Source: [Deprecations page](https://platform.claude.com/docs/en/about-claude/model-deprecations)
- Verified: November 6, 2026, against Anthropic's own pages
- Page: https://www.okapi.bot/models/anthropic/claude-sonnet-4-5/

## Anthropic's words

> API model name: claude-sonnet-4-5-20250929; Current state: Deprecated; Deprecated: September 30, 2026; Tentative retirement date: November 30, 2026

Okapi finds the calls this change hits in your repo and opens the pull request with the fix: https://github.com/apps/okapi-agent