Best Practices

Error Handling

Handle errors gracefully with proper status codes, meaningful messages, retry logic, and user-friendly responses.

Types of Errors

Client Errors (4xx)

Errors caused by invalid client requests. Client should fix the request.

400 Bad RequestInvalid data
401 UnauthorizedNot authenticated
403 ForbiddenNo permission
404 Not FoundResource missing
422 UnprocessableValidation failed
429 Too ManyRate limited
Server Errors (5xx)

Errors on server side. Server should handle and fix these.

500 Internal ErrorUnexpected error
502 Bad GatewayUpstream failed
503 UnavailableService down
504 TimeoutRequest timeout

Error Response Format

Consistent Error Structure

Basic Error Response

json

Validation Error Response

json

Server Error Response

json
Error Code Conventions
javascript

Error Handling Implementation

Custom Error Classes
javascript
Global Error Handler Middleware
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Async Error Handling
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Client-Side Error Handling

Retry Logic with Exponential Backoff
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Error Handling in API Client
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User-Friendly Error Messages
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Graceful Degradation

Fallback Strategies

Circuit Breaker Pattern

javascript

Fallback Data

javascript

Timeout Handling

javascript

Error Logging & Monitoring

Structured Logging
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Error Handling Best Practices
Use appropriate HTTP status codes: 4xx for client errors, 5xx for server errors
Consistent error format: Use same structure for all error responses
Meaningful error codes: Use descriptive codes like VALIDATION_ERROR, not E001
Never expose internals: Don't reveal stack traces or database details to clients
Include request IDs: Help users and support trace errors
Validate input early: Catch errors before processing
Implement retry logic: Use exponential backoff for transient failures
Provide fallback data: Cache responses for graceful degradation
Set request timeouts: Prevent hanging connections
Log all errors: Use structured logging for debugging
Monitor error rates: Set up alerts for unusual patterns
User-friendly messages: Translate technical errors for end users
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