Error page is a web page displayed when your website is non-functional. General errors are 400 (Bad request), 403 (Forbidden), 404 (Not Found), etc which has a per-defined error message. Custom error message is where you change those per-defined error messages and add a custom message or redirect it to a different website. Custom error page looks good rather than the traditional error page and you can even leave a message on that page.
You can create these custom error pages via your cPanel.
Step 1: Log in into your cPanel.
Step 2: Scroll down and search for “Error Pages” in “Advanced” section.
Step 3: Once you click on “Error Pages”, you will be on the below page. Enter the domain name for which you wish to create a custom error page in “Managing” below “Step 1 – Select Domain to Manage Error Pages”.
Click on the error option which you wish to customize and set a custom page.
Step 4: Once you click on the error option, you will be on the below page, where you can set a custom page/message for your viewers.
Click on “Save” option once you create a custom error page. The same custom error page will be displayed if that error strikes your website again.
In this way you can make a custom error page for any of your domain.