Site Preview from a domain in Plesk shows error 500: The server variable "HTTP_ORIGINAL_HOST" is not allowed to be set

Symptoms

• Site Preview on Plesk for Windows shows error 500.
• The following error is shown when the Site Preview is open directly on the server via Internet Explorer:

  CONFIG_TEXT: HTTP Error 500.50 - URL Rewrite Module Error.
  The server variable "HTTP_ORIGINAL_HOST" is not allowed to be set. Add the server variable name to the allowed server variable list.
  Detailed Error Information:
  Module RewriteModule
  Notification BeginRequest
  Handler ExtensionlessUrlHandler-Integrated-4.0
  Error Code 0x80070005

Cause

RewriteModule configuration on the server requires HTTP_ORIGINAL_HOST to be set on the server level.

Resolution

In order to resolve the issue, it is required to add the following set of variables via  IIS > SERVER_NAME > URL Rewrite > View Server Variables > Add:

CONFIG_TEXT: HTTP_ORIGINAL_HOST
HTTP_HOST
HTTP_ACCEPT_ENCODING
HTTP_IS_SITEPREVIEW

In order to do that, proceed as follows:

1. Log into the server via RDP.
2. Go to to Server Manager > Tools > IIS Manager > hostname > URL Rewrite > View Server Variables and click "Add";
3. Paste the HTTP_ORIGINAL_HOST variable there and click OK:
   
4. Repeat the above steps for HTTP_HOST, HTTP_ACCEPT_ENCODING and HTTP_IS_SITEPREVIEW variables as well.