Running the Python script for the Create Domain geoprocessing tool with ArcGIS for Desktop Background Geoprocessing (64-bit) installed returns the following error, "ERROR 000535: Workspace does not exist. Failed to execute (CreateDomain)."
Run the Python script from the Python window in ArcGIS for Desktop 10.4.1 Background Geoprocessing (64-bit) with PostgreSQL after disabling background processing in the Geoprocessing Options window.