I have the Default Print Widget loaded in my Web App Builder Application and it Errors out when trying to Print while in Web App Builder Developer and when I have it downloaded to my server. It is saying it can't connect to my map server. I can access the rest points of my services, and I can view and search them using other widgets within the same application. I can also access the Print Utility rest point without issues also at https://gis.adamscounty.org/arcgis/rest/services/Utilities/PrintingTools/GPServer/Export%20Web%20Map%20Task . I do not have my server locked down at all, so everything should be open. I am using ArcServer and Portal 10.3.1.
I have contacted ESRI support but they have yet to figure out why, and I think they are just grasping at anything with the suggestions they are making me try.