In the world of web development, understanding HTTP status codes is essential. These codes communicate the status of a request between the client and the server. This blog post explores 18 critical HTTP status codes you’re likely to encounter in common production scenarios. From the familiar 200 OK to the less common 505 HTTP Version Not Supported, we’ll delve into each code’s meaning and its implications for your web applications.
1. 200 OK
Success
- Description: The request succeeded. The server successfully processed the request and returned the expected data.
- Common Scenario: This is the most common status code indicating that everything is working as expected.
2. 201 Created
Resource Created
- Description: The request succeeded, and a new resource was created. Commonly used with POST/PUT requests.
- Common Scenario: When a new user is created in a database after a POST request.
3. 202 Accepted
Request Accepted
- Description: The request has been accepted for processing but not completed. Useful for async operations.
- Common Scenario: When a request is accepted but processing will take time, such as a batch job.
4. 204 No Content
Success, No Content
- Description: The server successfully processed the request but is not returning any content. Common in DELETE operations.
- Common Scenario: When a resource is successfully deleted from the server.
5. 301 Moved Permanently
Moved Permanently
- Description: The resource has permanently moved to a new URL. Search engines should update their links.
- Common Scenario: When a website changes its domain name.
6. 302 Found (Temporary)
Found (Temporary)
- Description: The resource is temporarily moved. The client should continue to use the original URL for future requests.
- Common Scenario: When a page is temporarily moved for maintenance.
7. 400 Bad Request
Bad Request
- Description: The server cannot process the request due to client error (malformed syntax, invalid request framing).
- Common Scenario: When the client sends an invalid request, such as a malformed JSON.
8. 401 Unauthorized
Unauthorized
- Description: Authentication is required. The client must authenticate with valid credentials.
- Common Scenario: When a user tries to access a protected resource without logging in.
9. 403 Forbidden
Forbidden
- Description: The server understood the request but refuses to authorize it. Authentication won’t help.
- Common Scenario: When a user tries to access a resource they don’t have permission to view.
10. 404 Not Found
Not Found
- Description: The server cannot find the requested resource. The URL is not recognized, or the endpoint is valid but the resource doesn’t exist.
- Common Scenario: When a user tries to access a non-existent page.
11. 408 Request Timeout
Request Timeout
- Description: The server timed out waiting for the request. The client didn’t complete the request in time.
- Common Scenario: When a request takes too long to process, such as a slow network connection.
12. 429 Too Many Requests
Too Many Requests
- Description: The user has sent too many requests in a given amount of time (rate limiting).
- Common Scenario: When a user exceeds the rate limit set by the server.
13. 500 Internal Server Error
Internal Server Error
- Description: The server encountered an unexpected condition preventing request fulfillment.
- Common Scenario: When an unhandled exception occurs on the server.
14. 501 Not Implemented
Not Implemented
- Description: The server does not support the functionality required to fulfill the request.
- Common Scenario: When a request is made for a feature that the server does not support.
15. 502 Bad Gateway
Bad Gateway
- Description: The server, acting as a gateway, received an invalid response from the upstream server.
- Common Scenario: When a proxy server receives an invalid response from another server.
16. 503 Service Unavailable
Service Unavailable
- Description: The server is temporarily unavailable due to overload or maintenance.
- Common Scenario: When the server is overloaded or undergoing maintenance.
17. 504 Gateway Timeout
Gateway Timeout
- Description: The server, acting as a gateway, timed out waiting for an upstream server response.
- Common Scenario: When a request takes too long to process and times out.
18. 505 HTTP Version Not Supported
HTTP Version Not Supported
- Description: The server does not support the HTTP protocol version used in the request.
- Common Scenario: When a client uses an outdated or unsupported HTTP version.
Understanding these HTTP status codes can significantly enhance your ability to diagnose and troubleshoot issues in a web production environment. Keep this guide handy as a quick reference for navigating the complex world of web server responses.