Hi there,
When I try and append a feature class to a feature layer using the append tool in ArcGIS Pro, it fails. It works when preserve global ids are unticked but I need the global ids to be preserved so I can append the related data. The error is - ERROR 999999: Something unexpected caused the tool to fail. Contact Esri Technical Support (http://esriurl.com/support) to Report a Bug, and refer to the error help for potential solutions or workarounds. Any help would be appreciated. Thanks!