404
404 is the code for Not Found.

Not Found
HTTP status code are three-digit status codes sent by a web server in response to a client’s URL request. These codes are part of the HTTP protocol and provide essential information about whether a request was successful, encountered an error, or requires additional action. They are categorized into five groups based on their first digit:
- 1xx (Informational): The request is received and is being processed.
- 2xx (Success): The request was successfully received, understood, and accepted.
- 3xx (Redirection): Further action is needed to complete the request, such as following a different URL.
- 4xx (Client Errors): The request was incorrect or cannot be fulfilled by the server, usually due to client issues.
- 5xx (Server Errors): The server failed to process a valid request due to an internal error.
Understanding the 404 HTTP Response Code
A 404 Not Found response code is one of the most well-known HTTP status codes. It indicates that the requested resource could not be found on the server. This typically happens when a user attempts to access a webpage or file that no longer exists, has moved without a redirect, or was never present at the URL.
Common Causes of a 404 Error
- The URL was mistyped or contains a broken link.
- The webpage has been deleted from the website.
- The URL structure has changed, but proper redirects (e.g., 301 or 302 redirects) were not set up.
- The server is misconfigured, preventing it from locating the requested file.
How to Handle a 404 Error
From a user’s perspective, encountering a 404 error means they should check the URL for mistakes or use the website’s navigation to find the correct page. From a website owner’s perspective, handling 404 errors effectively is crucial for user experience and SEO. Strategies include:
- Setting up custom 404 pages with helpful navigation or a search function.
- Implementing redirects for moved content using 301 or 302 redirects.
- Monitoring 404 errors using analytics tools and fixing broken links.
A well-managed 404 error can minimize users’ frustration and help maintain a website’s credibility and search engine rankings.
- Abbreviation: 404
- Source: What is a 404 Error?