HTTP error codes are standardized status responses sent by servers to indicate the result of a client’s request. Understanding them is essential for troubleshooting websites and APIs.
Error codes are grouped into categories:
- 1xx (Informational)
- 2xx (Success)
- 3xx (Redirection)
- 4xx (Client errors)
- 5xx (Server errors)
Most problems occur within the 4xx and 5xx ranges.
Common 4xx HTTP Errors
- 404 Not Found – The requested resource does not exist.
- 403 Forbidden – Access is denied.
- 400 Bad Request – The request is malformed.
These HTTP codes usually indicate an issue on the client side, such as incorrect URLs or missing permissions.
Common 5xx HTTP Error Codes
- 500 Internal Server Error – A general server failure.
- 502 Bad Gateway – Invalid response from upstream server.
- 503 Service Unavailable – Server temporarily overloaded.
These error codes suggest server-side problems.
Fixing Error Codes
To resolve them:
- Check server logs
- Verify configuration files
- Confirm DNS and routing settings
- Restart affected services
Monitoring HTTP errors regularly helps detect performance and availability issues early.
Why They Matter
Error codes impact:
- User experience
- SEO rankings
- Application reliability
Search engines may penalize websites with frequent 5xx errors, making it critical to address them promptly.
Conclusion
HTTP error codes provide valuable diagnostic information. By understanding what they mean and how to fix them, you can maintain a healthy and reliable web service.