To customize an error page, perform the following steps:
1 - Open cPanel (Your domain/Cpanel).
2 - Click on (Error Pages) from the Advanced section.
3 - If this account manages more than one domain, select the domain for which you wish to edit an error page from the Managing menu.
4 - Click the error status code for which you wish to edit its error page.
5 - Enter a message in the text box.
6 - Click Save.