Klaviyo Common Errors Overview Quick reference for the most common Klaviyo API errors with real error payloads, root causes, and solutions. Prerequisites - SDK installed - API credentials configured - Access to application logs Instructions Step 1: Identify the Error Klaviyo returns JSON:API error responses. Extract the status code and error detail: Step 2: Match and Fix --- 400 -- Bad Request (Validation Error) Actual Klaviyo response: Common causes: - Missing required field (email, metric name, list name) - Invalid phone number format (must be E.164: ) - Invalid filter syntax in query param…