I'm having an issue when attempting to upgrade a Electric UN to v4. Using Pro 2.6.3 and 'Update Dataset'. I've checked all features participating and none have any records with empty geometries. Getting this response:
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.
The operation was attempted on an empty geometry.
Failed to execute (UpgradeDataset).