HTTP 404 error refers to the fact that the web page pointed by the link does not exist, that is, the web address of the original web page is invalid, which often happens and is difficult to avoid. For example, the original URL address cannot be accessed due to the change of URL generation rules, the renaming or moving of webpage files, and the spelling error of imported links. When the Web server receives a similar request, it will return a 404 status code, telling the browser that the requested resource does not exist.

404 error page

Generally speaking, there are three reasons for this error:

1. Unable to access the website on the requested port.

2. The 2.Web service extension locking policy blocked this request.

3. The 3.MIME mapping policy blocked this request.