Best Practices for REST API Error Handling

Error handling in REST APIs is crucial for building robust, user-friendly, and maintainable services. Below are key practices with practical implementations.

🔷 Document Error Responses

• Use OpenAPI/Swagger to document all possible error responses.
• Example YAML snippet:

  responses:
  400:
  description: Bad Request
  content:
  application/json:
  schema:
  $ref: '/components/schemas/ErrorResponse'
  

🔷 Use Standard HTTP Status Codes

• Common HTTP codes:
  – `200 OK` – Success
  – `400 Bad Request` – Invalid input
  – `401 Unauthorized` – Missing/auth failed
  – `404 Not Found` – Resource missing
  – `429 Too Many Requests` – Rate limit exceeded
  – `500 Internal Server Error` – Server failure

🔷 Provide Meaningful Error Messages

• Bad: `{“error”: “Invalid request”}`
• Good:

  {
  "error": "Validation failed",
  "details": "Email must be a valid format"
  }
  

🔷 Use a Consistent Error Format

• Standard JSON structure:

  {
  "code": "ERR-4001",
  "message": "Invalid API key",
  "timestamp": "2025-06-04T12:00:00Z",
  "requestId": "req-123456"
  }
  

🔷 Include Error Codes

• Machine-readable codes help automate client-side handling.
• Example: `ERR-5002` for database failures.

🔷 Provide Contextual Information

• Log errors with `requestId` for tracing:

  Linux command to filter logs
  grep "req-123456" /var/log/api/errors.log
  

🔷 Rate Limiting Responses

• Return `429` with `Retry-After` header:

  HTTP/1.1 429 Too Many Requests
  Retry-After: 60
  

🔷 Log Errors

• Use structured logging (e.g., ELK Stack):

  logger -p local0.err -t API "Error 500: Database connection failed"
  

You Should Know:

Linux Commands for API Debugging

1. Test API with `curl`:

curl -X GET https://api.example.com/users -H "Authorization: Bearer token"

2. Monitor API logs:

tail -f /var/log/api/access.log | grep "500"

3. Rate limit testing:

ab -n 100 -c 10 https://api.example.com/resource

Windows Commands

1. Check HTTP responses:

Invoke-WebRequest -Uri "https://api.example.com" -Method GET

2. Parse JSON errors:

(Invoke-RestMethod -Uri "https://api.example.com").error | Format-Table

What Undercode Say:

Effective error handling ensures smoother integrations and faster debugging. Always:
– Use standardized formats.
– Log comprehensively.
– Test edge cases with tools like `Postman` or curl.

Prediction: APIs with clear error handling will see 30% fewer support tickets and faster adoption.

Expected Output:

{
"status": "success",
"message": "Error handling implemented"
}

Relevant URL: REST API Error Handling Best Practices

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