claude-3-haiku-20240307 just started returning errors — here's what happened

If your code hits claude-3-haiku-20240307 and started failing yesterday, you're not alone. Anthropic retired Claude Haiku 3 on April 20, 2026. Retired, not deprecated — requests to the old model ID no longer complete. They return an error. This is a real deprecation cutoff that was announced 60 days ago and landed without much fanfare. If you missed the email, you're finding out now — probably from a production alert, or worse, from a user telling you the product is broken. What the failure look