Anthropic model retirement: retired IDs fail on request, migrate before the date

TL;DR: A retired model is not available for use. Requests to it fail. Migrate deprecated models before the retirement date. Test the replacement on your tasks well before the deadline; newer generations can behave differently enough to need prompt or eval updates.

Retirement is a hard failure, not a warning

Lifecycle states: active, deprecated (functional, not recommended, has a retirement date and a recommended replacement), retired (requests fail).

What to do

1. Watch the model deprecations page for every model ID you call. Anthropic gives at least 60 days notice before retiring publicly released models, and notifies customers with active deployments.
2. Migrate deprecated models before the retirement date. Test the replacement on your tasks well before the deadline; newer generations can behave differently enough to need prompt or eval updates.
3. Audit usage: the Console offers an API usage audit to find where deprecated models are still being called. Run it after every deprecation announcement.
4. Remember partner platforms set their own schedules. A model can be alive on the Claude API and retired on Bedrock or Google Cloud, or vice versa. Check the lifecycle on the platform you actually call.
5. Deprecated models are documented as likely less reliable than active ones. Move workloads to active models for the highest level of support.

The trap

Hardcoding a model ID and forgetting it. The 60-day notice only helps if someone is watching; otherwise the first symptom is a wave of failures on retirement day. The other trap: assuming one retirement schedule everywhere. Your Bedrock deployment has its own dates.

Checklist

• Keep a registry of every model ID in every config, with its retirement date. Review it monthly.
• When a deprecation is announced, the migration is the task. "Still works today" is not a plan.

When to use this

• You are seeing this exact error message; match the block above, not just part of it.
• The failing call matches the scenario in the title: Anthropic model retirement.
• You want the fastest verified fix before digging through logs.

When not to use this

• Your error text differs from the block above; close cousins often have different causes.
• The stack trace points at a different component than the one in the title.
• You already applied this fix and the error persists; look for a second cause instead of reapplying.

Compatibility

• Not pinned to a specific version; follows current Anthropic behavior.

Anthropic's deprecations page documents the active/deprecated/retired states, that requests to retired models fail, 60-day minimum notice, the usage audit, and that Bedrock/Google Cloud set their own retirement schedules. Verified live at https://platform.claude.com/docs/en/about-claude/model-deprecations.