400 is the most common error that you may encounter when visiting a server, as the server is unable to process the request that is being passed on by your browser because of an incorrect syntax or broken cookies, or a wrong URL format. Error 400 tends to refer to the malformation of something in the request so that the server cannot process it. Some of the common tools used to correct this problem include clearing the cache data, verifying that the URL is correct, and ensuring that your request is properly formatted.