Claude Mythos Preview retirement date: to be announced
claude-mythos-preview is deprecated; the retirement date is to be announced.
- Provider
- Anthropic
- Model IDs affected
claude-mythos-preview- Announced
- June 9, 2026
- Shutdown date
- To be announced
- Replacement
- None listed
- Platforms
- Dates apply to the Claude API and other Anthropic-operated platforms. Amazon Bedrock and Claude Models on Google Cloud (Google managed) set their own retirement schedules, so check those model tables separately.
- Source
- Official Anthropic deprecations page (data last changed 2026-11-02, re-checked daily)
Migrating from Claude Mythos Preview
Not yet reviewed. We haven't written model-specific migration notes for Claude Mythos Preview yet. Start with the provider's official guidance, and use this general checklist:
- Search your code, config and environment variables for
claude-mythos-preview. - Re-run your evaluation set against the replacement before switching traffic.
- Recount tokens with the new model's tokenizer and re-check
max_tokens, context fit and cost. - Check tool calling, structured output and stop sequences on your real prompts.
- Dates apply to the Claude API and other Anthropic-operated platforms. Amazon Bedrock and Claude Models on Google Cloud (Google managed) set their own retirement schedules, so check those model tables separately.
Check your code before the shutdown
All model retirements · All Anthropic deprecations
FAQ
When will Claude Mythos Preview be retired?
Claude Mythos Preview is deprecated, but its retirement date is to be announced (see the official Claude API deprecations page). Subscribe to the calendar feed to hear when it’s set.
What happens to claude-mythos-preview requests after the shutdown date?
After a model is retired, API requests to it return an error. Move traffic to the replacement and test it on your own prompts before the date.
Does this date apply to Amazon Bedrock, Vertex AI or Azure?
Dates apply to the Claude API and other Anthropic-operated platforms. Amazon Bedrock and Claude Models on Google Cloud (Google managed) set their own retirement schedules, so check those model tables separately.