Anthropic Retires Claude Haiku 3, Requires Developers to Migrate to Haiku 4.5
Anthropic is phasing out older Claude models and standardizing its low-latency, low-cost API applications on the newer Haiku 4.5. The retirement of Haiku 3 is more than a routine upgrade. It also underscores the need for companies to track model versions, conduct compatibility testing and manage model life cycles to prevent service disruptions.
Anthropic formally discontinued Claude Haiku 3 on April 19, 2026, requiring developers to update their API model IDs to Haiku 4.5. The migration includes breaking changes involving parameter settings and refusal-response handling. Existing systems must undergo code modifications and testing before they can transition reliably.
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The history behind this eventAnthropic Works to Restore Claude Models After Service Disruptions
Anthropic’s Claude models underpin its consumer chatbot, the Claude Code developer tool and applications connected through the Claude API. A disruption spanning those products can affect more than individual conversations, potentially interrupting software development and automated business workflows that rely on Claude. The incident highlights the operational risks facing users that depend on a single artificial-intelligence provider or model family.
Anthropic reported elevated request error rates affecting multiple Claude models, alongside disruptions to claude.ai, Claude Code and the Claude API. The company said it had identified the cause and begun remediation, while affected users temporarily shifted work to other models. Anthropic had not disclosed the number of users affected, the precise start of the incident or a timetable for full service restoration.
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