Custom errors on the Linux platform are created by using the '.htaccess' file. This file simply tells the Webserver (Apache) how to handle specifed error.To create a .htaccess file open a text editor such as notepad and add the following lines:
ErrorDocument 403 /custom_error_to_be_displayed.html
ErrorDocument 404 /custom_error_to_be_displayed.html
Unless you are competent in the NFS(Network File System) file system please upload all the pages specifed in the .htaccess file in the root of your home directory. NFS is case sensitive, so ensure that you specify the correct file, Error404.html is not the same as error404.html.Once you have created the .htaccess file upload this into the root of your home directory and this file will be automatically active.
Once these have been installed you can test this simply by browsing to a page that will reproduce an error in your domain that you have installed a custom error for. For example testing a 404 error, browse to http://www.domain.com/page_that_does_not_exist and rather than getting a 404 error message you should get the page that you have specified.
Setting up any other custom errors to handle errors other than 40, 402, 403 and 404 will result in difficulty debugging your domain and we do not recommend this.