In order to set up custom error,please do the following:
TURNING ON CUSTOM ERROR PAGES :-
Before you can use custom error pages, you must first turn them on.
1. Login to the Plesk.
2. Go to the Websites & Domains tab.
3. On the list of domain name at the bottom, click on the domain name you are configuring.
4. Check the box for Customer error documents.
5. Click OK.
You will be taken back to the Websites & Domains tab and it should say "Information: The settings were successfully updated" near the top of the page.
Once you have Custom Error Pages turned on, you have two options for setting them up: edit the existing error documents, or create new ones.
OPTION 1: EDITING AN EXISTING CUSTOM ERROR PAGE
The easiest way to create your own error page is to edit the ones already there.
1. Click on the Website & Domains tab.
2. Click on File Manager icon.
3. Click on the error_docs folder (the text link or the folder in front of the link).
4. Click on the error page you want to edit. For example, test_testing.html.
5. Use Plesk's built-in HTML editor to edit the error page.
6. Click OK to save the changes.
Once saved, your changes will take effect.
OPTION 2: SETTING UP CUSTOM ERROR PAGES
Instead of editing the existing error pages, you can create your own with different file names, or even specify that it redirects to a specific URL instead.
STEP 1: CREATING THE NEW ERROR PAGE
Create a new page and upload it to your domain. It can be named anything, and can be in any supported language such as HTML, PHP, ASP and ASP.NET.
You can use the File Manager in Plesk to create a new file, and then edit it, or create it on your own computer and then FTP it to the server.
STEP 2: SETTINGS TO USE THE NEW ERROR PAGE
1. Click on Websites & Domains tab.
2. Click on Show Advanced Options (grey link near the middle of the page) if the advanced options are not already shown.
3. Click the Virtual Directories.
4. Click on the Error Documents tab.
5. Click on the Error Document you wish to change.
6. Set the options for that error:
7. Click OK.
