SharePoint 2013 + "Entry point not found " error while opening the workflows in Visio

Error: Entry point not found (or) The Server failed to process the request when I tried to open the SharePoint 2013 workflows tasks status in Visio.

Solution: "Visio Graphics Service" was not running(Start it from Central Admin site -->Services on Server --> Find Visio Service), which was causing this problem. Starting the service resolved it.