How to Look Up HTTP Status Codes

Problem

You received an HTTP status code and need to understand what it means and how to handle it.

Prerequisites

• Basic understanding of HTTP
• Knowledge of client-server architecture

Steps

1. 1. Identify the status code category

   HTTP status codes are grouped by their first digit: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error. The category tells you whether the request succeeded and where the problem lies.

   Input

   404

   Output

   4xx: client error

2. 2. Look up the specific code

   Find the specific meaning: 200 OK (success), 201 Created (resource created), 301 Moved Permanently (redirect), 404 Not Found (resource missing), 500 Internal Server Error (server fault). Each code has a defined semantics in the HTTP specification.

   Input

   404

   Output

   Not Found: the requested resource does not exist

3. 3. Handle the response appropriately

   Based on the code, decide how to handle the response: 2xx means proceed with the data, 3xx means follow the redirect, 4xx means fix the request, 5xx means retry or report a server issue. Some codes (like 429 Too Many Requests) require specific handling like backoff.

   Input

   429 Too Many Requests

   Output

   apply exponential backoff and retry

Expected result

Understanding of the status code's meaning and the appropriate client-side handling.

Common errors

Treating all 4xx as user error

Some 4xx codes require different handling: 401 needs authentication, 403 means forbidden even with auth, 429 needs rate limiting. Handle each specifically.

Not following redirects (3xx)

3xx codes indicate the resource moved. Follow the Location header to get the new URL, unless redirect following is disabled for security.

Troubleshooting

• If a 5xx error persists, the server has a problem. Contact the API provider or check server logs.
• For 401/403, verify authentication credentials and permissions.

Security limits

• Do not automatically follow redirects to untrusted hosts. Validate the redirect target.