Try this for now: var json = "{ \"url\": \"https://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/USA_Counties/FeatureServer\" }"; var portalItem = new PortalItem(json, portal); portalItem.Title = "TEST_FS"; portalItem.Type = PortalItemType.FeatureService; portalItem.Tags.Add("TES"); portalItem.Tags.Add("Wakim National Forest"); portalItem.Tags.Add("Endangered species"); // Set all needed properties on the item await portal.User.AddPortalItemAsync(portalItem); I guess the trick is to create the portal item from JSON that contains only the URL (could contain any other properties from the REST spec as well I suppose) and set all the other properties on the resulting portal item before adding it to the portal.
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