Anthropic Common Errors

Overview

Quick reference for all Claude API error types with exact HTTP codes, error bodies, and fixes. The API returns errors as JSON: {"type": "error", "error": {"type": "...", "message": "..."}}.

Error Reference

400 — invalid_request_error

{"type": "error", "error": {"type": "invalid_request_error", "message": "messages: roles must alternate between \"user\" and \"assistant\""}}

Common causes and fixes: