Why am I getting 'model not found' errors with Claude 4?

After June 15, 2026, the model IDs 'claude-4-opus' and 'claude-sonnet-4' are no longer valid. The API returns a 'model not found' error because those model names have been retired. Replace them with 'claude-opus-4-8' or 'claude-sonnet-4-6'.

What does the Claude 4 deprecated model error look like?

The error response typically includes: {"type":"error","error":{"type":"invalid_request_error","message":"model 'claude-4-opus' is deprecated"}}. The HTTP status is 410 Gone. The fix is to update the model name string in your code.

Will my Claude API key still work after the Claude 4 deprecation?

Yes. Your API key remains valid. Only the model name strings are retired. Use the same API key with 'claude-opus-4-8', 'claude-sonnet-4-6', or any other current Anthropic model.

How do I fix Claude 4 API errors in Python?

Find every instance of model='claude-4-opus' or model='claude-sonnet-4' in your Python code and replace with model='claude-opus-4-8' or model='claude-sonnet-4-6' respectively. Also check .env files for ANTHROPIC_MODEL variables.

Can I use Claude 4 after June 15 if I haven't migrated?

No. After June 15, 2026, all API calls to Claude 4 Opus and Claude Sonnet 4 fail with errors. There is no grace period. You must update your code to use Claude Opus 4.8 or Claude Sonnet 4.6.

Claude 4 API Errors After June 15: How to Fix Them

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