A 404 error is generated by an Internet browser when a web page or a website can't be found on a server. Generally, a 404 error is considered a client-side error and can be generated by user error, such as an incorrect uniform resource locator, better known as a URL.
A 404 error also is generated when web administrators fail or forget to redirect an old page URL to any new pages created to replace it. This error code is considered an HTTP status code and also can be generated by the Windows Update program as error code 0x80244019. As of 2014, the 404 error code can appear on any type of operating system and Internet browser.