The Error 404 "Page not found" is the error which time you search xyz URL in browser but page in not uploaded in FTP that time you facing this problem first upload pages after that you solve this problem
Pop this code into your .htaccess file: 1) Errordocument 404 /404.html 2) Create custom 404 page called 404.html 3) Upload 404.html to your site's root directory. It sometimes varies from hosting platform to platform, but generally that's how to display a custom 404 page. Hope that helped!
Suppose your website name is abc.com and wen you type in address bar abc.com/223 If you have created error page then whatever user type in a address bar it will reflect 2 ur error page that means search engine doesn't found that this page doesn't exits