I have WebApp application I am creating with the Developer Edition. In ArcMap I created a custom print service like described here (https://enterprise.arcgis.com/en/server/latest/create-web-apps/windows/tutorial-publishing-additional-services-for-printing.htm). When I use the custom PrintService in the Print Widget, no file is exported but an error is thrown: Error executing tool. Export Web Map.
When I copy the Web_Map_as_JSON code that is generated, remove the basemap layer (https://services.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer), I can get the PrintService to work when I start from REST endpoint (execute) in the ArcGIS Server Manager.
However, the combination of MapServices (hosted on an internal server) and the ESRI basemap does not seem to work.
When I use the standard PrintService of WAB, I can get an export when I deselect all layers and only print the basemap, but when I add layers of my MapServices, it fails.
Any idea what has to be done to make the print widget working with a custom PrintService?