Unable to configure ArcGIS Web Adaptor (IIS) for ArcGIS Enterprise 11.1

Description

After installing ArcGIS Web Adaptor (IIS) for ArcGIS Enterprise 11.1, attempts to open the configuration page fail, and the following error message is returned.

Error:   
HTTP Error 500.19 - Internal Server Error
The requested page cannot be accessed because the related configuration data for the page is invalid.

Cause

The ArcGIS Web Adaptor machine does not have the prerequisites installed. The prerequisites for ArcGIS Web Adaptor 11.1 are different from the previous ArcGIS Web Adaptor versions.

Solution or Workaround

Install the prerequisites required on the machine before attempting to configure ArcGIS Web Adaptor 11.1. Refer to ArcGIS Enterprise: Prerequisites for more information.