Hyper-V BACKUP VM commands with mode FULL are not allowed on hosts where the Data Protection for Microsoft Hyper-V license file is installed. Instead, issue the BACKUP VM command using mode IFFULL or IFINCR.
If you must issue the BACKUP VM command with mode FULL, you must uninstall the Data Protection for Microsoft Hyper-V license file. However, uninstalling the license file invalidates the IFINCR backup chain. As a result, an IFFULL is performed if the Data Protection for Microsoft Hyper-V license file is reinstalled.
The backup does not start.
Try the operation again and specify mode IFFULL or IFINCR.