Consistent error handling makes APIs predictable and debuggable. Here's how to implement it effectively.
Error Response Structure
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Custom Error Classes
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Express Error Middleware
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HTTP Status Codes
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Error Codes
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Retry Headers
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Logging Errors
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Best Practices
Response Format:
✓ Consistent error structure
✓ Machine-readable error codes
✓ Human-readable messages
✓ Include request ID
Status Codes:
✓ Use appropriate HTTP status
✓ 4xx for client errors
✓ 5xx for server errors
✓ Don't use 200 for errors
Security:
✓ Don't leak internal details
✓ Sanitize error messages
✓ Log full details server-side
✓ Use generic messages for 500s
Recovery:
✓ Include retry information
✓ Suggest corrective actions
✓ Provide documentation links
✓ Handle timeouts gracefully
Conclusion
Consistent error handling improves API usability and debugging. Use custom error classes for different error types, return appropriate status codes, and include enough information for clients to understand and handle errors. Always log full details server-side while returning safe messages to clients.