How do I migrate from Claude 4 Opus to Claude Opus 4.8?

Change the model name from 'claude-4-opus' to 'claude-opus-4-8' in your code. Your API key, SDK, endpoint, and authentication all stay the same. It's a one-line change. Claude Opus 4.8 is 67% cheaper ($5/$25 vs $15/$75 per million tokens) with a 5x larger context window (1M vs 200K).

What happens if I don't migrate by June 15?

After June 15, 2026, API calls to 'claude-4-opus' and 'claude-sonnet-4' return errors. Your API key still works — you just need to update the model name string. If you're using the Anthropic SDK, update to the latest version which includes the new model IDs.

How long does it take to migrate from Claude 4?

For a direct replacement (Claude Opus 4.8 or Sonnet 4.6), migration takes 5-15 minutes — it's a one-line code change. For cross-provider migration (GPT-5, DeepSeek, Gemini), allow 1-2 hours for API changes, testing, and validation. Budget 1-2 weeks for parallel testing before full cutover.

Can I test the new model before switching?

Yes. Run both models in parallel on the same prompts for 1-2 weeks. Compare output quality, latency, and cost. Use environment variables to switch between models without code changes: MODEL_NAME=claude-opus-4-8 in your .env file.

Claude 4 Migration Guide: Step-by-Step Before June 15

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