# Error Handling Reference

Common issues and solutions:

**Schema Validation Failures**
- Error: Request body does not match expected schema
- Solution: Add detailed validation error messages; provide schema documentation; implement request sanitization

**Authentication Errors**
- Error: Invalid or expired authentication tokens
- Solution: Implement proper token refresh flows; add clear error messages indicating auth failure reason; document token lifecycle

**Rate Limit Exceeded**
- Error: API consumer exceeded allowed request rate
- Solution: Return 429 status with Retry-After header; implement exponential backoff guidance; provide rate limit info in response headers

**Database Connection Issues**
- Error: Cannot connect to database or query timeout
- Solution: Implement connection pooling; add health checks; configure proper timeouts; implement circuit breaker pattern for resilience