KB42380: "Image file not found" or "The background image cannot be found" error occurs when running an exported Report Service Document in mht format containing an Image Layout Widget in MicroStrategy Web

SYMPTOM:
From Strategy 9.3.0, a new widget Image Layout is introduced. Besides the out of the box maps, custom maps can be included. Refer to How to Add a Custom Coordinates File for the Image Layout Widget in MicroStrategy Web 9.3.0 to add custom maps. An error happens when running the exported document in mht format if the map has an embed image using SRC parameter. For example:
The coordinates file contains an image link:
 

<IMG src="../VisFramework/map/Custom.jpg" USEMAP="#myMap" WIDTH="812" HEIGHT="713" BORDER="0" /><MAP NAME="myMap">

9.4.1:

9.3.1:
Image file not found
 
9.4.1:
The background image cannot be found