HTTP Status Codes

HTTP Status Codes

HTTP status codes are three-digit response codes sent by a web server to indicate the result of an HTTP request.

When a browser requests a webpage, image, stylesheet, script, or other resource, the server responds with an HTTP status code. These codes indicate whether the request succeeded, requires further action, encountered a client-side problem, or failed because of a server-side problem.

HTTP Status Code Classes

The first digit of an HTTP status code identifies its response class. Status codes are grouped into five categories ranging from informational responses through server errors.

1xx Informational

Informational status codes indicate that the request has been received and that communication or processing is continuing. These responses are generally handled automatically by browsers and other HTTP clients.

2xx Successful

Successful status codes indicate that the server received and successfully handled the request.

3xx Redirection

Redirection status codes indicate that the client may need to use another location or take additional action to complete the request. Some 3xx responses are also used for HTTP caching.

4xx Client Errors

Client error status codes indicate that the server cannot fulfill the request because of the request itself, authentication or authorization requirements, the requested resource, or another client-related condition.

5xx Server Errors

Server error status codes indicate that the server is aware that it encountered an error or cannot perform the requested operation.

Common HTTP Status Codes

A smaller group of status codes appears frequently during normal website development, testing, redirects, and troubleshooting.

404 Not Found

The 404 Not Found response is one of the most familiar HTTP status codes. It indicates that the server cannot find a current representation of the requested resource or is not willing to disclose that one exists.

A 404 response can occur when a URL is typed incorrectly, a link points to a nonexistent location, a file has been deleted, or a resource has been moved without an appropriate redirect.

Websites can provide a custom 404 page to help visitors recover by offering useful navigation, a link to the home page, or another way to locate the desired content. The server should still return the actual 404 HTTP status code for a missing resource rather than returning a normal 200 OK response for the error page.

HTTP Redirects

Redirect status codes tell a browser or other client that a resource is available at another URL. The appropriate redirect depends on whether the move is permanent or temporary and whether the original HTTP request method needs to be preserved.

Permanent redirects are commonly used when a webpage has permanently changed URLs. Correct redirects help visitors, browsers, and search engines reach the replacement resource.

HTTP Status Code Best Practices

• Return 200 OK only when the request has been successfully handled as intended.
• Return an appropriate 404 Not Found status when a requested resource cannot be found.
• Use permanent redirects when a resource has permanently moved and temporary redirects when the change is temporary.
• Avoid long redirect chains that make browsers request several URLs before reaching the final resource.
• Do not return a 200 OK status for a page that is actually reporting that a resource was not found.
• Use 401 Unauthorized for HTTP authentication requirements and 403 Forbidden when the server refuses to fulfill an understood request.
• Use 5xx responses for server-side failures rather than presenting them as successful requests.
• Check HTTP response headers when troubleshooting missing pages, redirects, caching, and server errors.