What are Error Pages?
The origin story of the 404 page goes back to the 1980s in Switzerland where scientists at CERN worked on the development of the world wide web1. They worked on the fourth floor, the same floor that held the central database in room “404”, where they were tasked with responding to requests by allocating files and manually transferring them across the web. Many people failed to input the correct data, and this repeated occurrence prompted them to create a stand message for these faulty requests: “Room 404: file not found.” The popularity of this message endured through the 80s and in 1992 the World Wide Web Consortium (W3C) introduced the use of HTTP status codes, formalizing and eternalizing this message. In HTTP spec, 4 is the error class (client error) and 04 is the specific error (not found).
HTTP code spec has five recognized classes of errors:
- 1xx: Informational: Request received, continuing process.
- 2xx: Success: The action was successfully received, understood, and accepted.
- 3xx: Redirection: Further action must be taken in order to complete the request.
- 4xx: Client Error: The request contains bad syntax or cannot be fulfilled.
- 5xx: Server Error: The server failed to fulfill an apparently valid request.
The following are the five most common error codes:
404 Not Found. The 404 status code means that the requested resource is no longer available or, specifically, “not found.” A common reason for a 404 error is a typo. An extra or missing letter in a URL that was manually typed, or a wrong domain name, can result in an error of this type. Another common reason for this error is clicking on an aged secondary link that is attempting to take you to a page that no longer exists.
403 Forbidden. A 403 status code returned from an HTTP request means access to the resource is forbidden. This is not a problem with authentication, as those are 401 (unauthorized) errors. A common reason for a 403 error is the server maintains a whitelist of machines that can access the system, and the machine requesting the page is not on that list. Another reason for a 403 error is that the certificate is missing or is no longer valid.
500 Internal Server Error. The 500 status code is the default error for when a specific problem is not identified.
503 Service Unavailable. The 503 status code is generally a temporary problem. It means the web server isn’t available.
504 Gateway Timeout. The 504 status code indicates a gateway timeout, clearly. A proxy server must communicate with a secondary web server and access to that web server has timed out. Reasons may include a DNS issue, the web server may be overburdened, or a network device may be down.
1 Akpobi, 2020, “The Brilliant Story Behind the Error 404 Message”