To set up custom error pages on your Windows shared hosting account, you will first need to log in to the Blacknight control panel at cp.blacknight.com. From there, browse to Hosted Domains (or Websites) >> Domainname >> Website Configuration >> Error Documents. On this page you can manage how the site will treat each error type.
To set up a custom error page, select the error type you wish to set up a custom page for.
You will then be presented with the following options:
If you are using static custom error files (HTML files), you should always use the File option.
Place the page you will want to be served as the error page in the /errdocs/ folder of your hosting and specify the file name in the File box, as shown above.
If you plan to develop an application (by using ISAPI or ASP) to handle errors, then use the URL option.
Note that the error status is handed to the application in the URL parameters and it is the applications responsibility to set the HTTP header status; otherwise, the HTTP response status will be "HTTP 1.1 200 OK."
Please note that this configuration is applied across the entire webspace, so any sites hosted in the same webspace will share these settings.
If you wish to set different error pages for different sites, you will need to ensure that they are hosted in separate webspaces. For information on moving your site into a different webspace, please refer to the following article: https://help.blacknight.com/hc/en-us/articles/212522989-Changing-Webspace