Claude 4 Opus and Claude Sonnet 4 stopped working on June 15, 2026. After this date, API calls return errors.
No. Your existing Anthropic API key works with all current models including Claude Opus 4.8 and Claude Sonnet 4.6. No key rotation or regeneration is needed.
DeepSeek V4 Pro at $0.435/$0.87 per million tokens is the cheapest option — 98% less than Claude 4 Opus. However, it requires switching providers and using a different SDK. The cheapest Anthropic option is Claude Haiku 4.5 at $1.00/$5.00 per million tokens.
No. After June 15, 2026, API calls to Claude 4 Opus and Claude Sonnet 4 return errors. There is no grace period.
Yes. Claude Opus 4.8 and Claude Sonnet 4.6 are backward-compatible with Claude 4 prompts. The API interface is identical — only the model name string changes. We recommend testing your prompts to verify output quality.
The code change itself takes seconds — it's a one-line model name update. Most teams complete the full migration (including testing) in under an hour. Larger applications with extensive prompt chains may need a day of testing.
For the easiest migration, upgrade within Anthropic to Claude Opus 4.8 or Sonnet 4.6 — same SDK, same API key, no provider switch needed. For maximum cost savings, consider DeepSeek V4 Pro (98% cheaper) or GPT-5 (89% cheaper), but factor in the migration effort of switching SDKs.
The deprecation only affects model availability — not your data. Your API key, account, billing, and any stored conversations remain unchanged. The new models (Opus 4.8, Sonnet 4.6) use the same infrastructure.
No. Only Claude 4 Opus and Claude Sonnet 4 were deprecated. Claude Haiku 4.5, Claude Opus 4.8, Claude Sonnet 4.6, and Claude Opus 4.7 all remain available.
Related Resources
- 🚨 Claude 4 Is Down — 5-Minute Fix Guide
- Claude 4 Stopped Working? — Quick fix guide if your API calls are already failing
- Claude Deprecation Calculator — Calculate your exact migration cost and savings
- Claude 4 Migration Tool — Compare all 67 alternatives with your exact usage
- Claude 4 Migration Guide — Step-by-step code examples in Python, Node.js, and REST API
- Best Claude 4 Alternatives — Detailed comparison of all replacement options
- Claude 4 Deprecation Countdown — Live countdown and timeline
- Model Deprecation Timeline — Visual lifecycle of every AI model
- AI Model Deprecation Guide — How to handle model retirements in general
- LLM Pricing Comparison — Compare all 82 models across 10 providers
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