ArcGIS Server .NET Web Applications display a red 'X' instead of the image for a task result

Description

After executing a task in an ArcGIS Server .NET Web Application, a red 'X' is displayed near the feature in the map display, in place of the image that is set to display for a layer's result symbol.

Cause

The path to ArcGIS Server's Marker Symbols directory is broken or nonexistent. By default, this folder is found in the following location:
<application root directory>\aspnet_client\ESRI\WebADF\MarkerSymbols

Solution or Workaround

• Re-create the ArcGIS Server Instance that is serving the application. For more information about re-creating the ArcGIS Server instance, please refer to the articles in the Related Information section below.
• Copy the ESRI folder from the <application root directory>\aspnet_client folder on a working application server, and paste it into the aspnet_client folder for the application server that is not working correctly.