Web development

HTTP error codes: A guide.


The internet as we know it today is a complex place and with over a billion websites serving up tons of data to users every second, it’s easy to see how an error may sometimes occur. When trying to access a website online, it’s common to be presented with what is known as an HTTP error code. When you receive one of these codes, it is signalling a failure to provide you with entry to a certain domain or page on a website. To understand what the error is and what needs to be done to fix it, the server will send out a specific type of error code in relation to the issue.

Here, we take a look at the most commonly seen HTTP error codes, explain what they mean and how to fix them.

Identifying what each code means
The class of many HTTP error codes can be quickly identified by their first digit. A good rule of thumb is that codes beginning with a ‘4xx’ are from the website CMS itself – WordPress, Magento or another CMS that your website is built in. Meanwhile, codes starting with ‘5xx’ are problems on the server side.

  • 1xx: Informational codes indicate that a request has been initiated and continued by the browser.
  • 2xx: Success codes are when a browser request has been successfully received, understood and processed by the server.
  • 3xx: Redirection codes are returned when the requested resource has been substituted by a new source.
  • 4xx: Client error codes indicate there is a problem with a request to the server.
  • 5xx: Server error codes highlight an error on the server that is preventing the fulfilment of an accepted request.

There are hundreds of error codes and solutions, which can become confusing and time-consuming for most people to understand. But below we’ve listed out some of the most common ones you’re likely to come across:

404 Not Found
One of the most frequently seen HTTP error codes on the web, a 404 error suggests that the web page you are trying to access could not be found on the server. This is a client error code incident, which usually means either the page has been deleted or moved and not properly redirected or you have misspelled the URL.

401 Unauthorised
This code indicates the requested resource is restricted and requires authentication. The most common cause of receiving a 401 error code is inputting an incorrect URL, so make sure you check this initially. Other solutions to resolving this error code could be clearing your browser cache and cookies, check for unexpected database changes or uninstall any new plugins and extensions from the site.

403 Forbidden
If you see a 403 Forbidden error code when trying to access a webpage, it means that access to the page or resource is not permitted on any grounds. Causes for this error include content not uploaded to the correct directory on the server or it could be permission-based (incorrect ownership or permissions of the web content files).

500 Internal Server Error
This error code is a collective status code for server errors and tends to be the most common of its kind. If reloading the webpage and clearing your browser cache doesn’t fix this (it could be an old cached version of the page you are viewing), you will need to check the error log button in the cPanel. If your website is managed by an external company, get in touch to log the error.

502 Bad Gateway
This error code means the server received an invalid response while working as a gateway to handle the user request. The cause of a 502 error could be faulty programming, server software timeouts, a sever overload or similar issues. Using a service such as this one will help you quickly understand if it is an issue isolated to your website or more widespread. Keep a log of the error if it regularly appears and be sure to notify the person who manages your website.

503 Service Unavailable
Usually occurring when the server is being overloaded or maintenance is being carried out on a site, the 503 error code tends to be temporary. The server is actually still functioning properly but has returned a 503 response to alleviate some pressure.

504 Gateway Timeout
This error signals that a web server didn’t receive a quick enough response from another server when attempting to load content. There are various causes for this error code to be relayed to the user, including connectivity issues, changes to the DNS, firewall configurations or bugs in a website’s code.

Now you know a little more about these specific error codes it should aid you in troubleshooting any issues accessing a website. If it is an external website as opposed to your own, try and find the time to notify the company as they may not be aware of the issue. If you need help resolving an error code on your website and someone will be happy to help.

Written by Ruby Ribbons
Senior account manager, social secretary and resident 'baller'.