You must configure external storage for the domain backups.
Verify that an external (secondary) IP-based storage is connected to the management domain.
Verify that you have an image-level backup appliance that is integrated with VMware vSphere Storage APIs - Data Protection, and is compatible with the vSphere version used by the management domain available and installed on the management domain.
Verify that the backup appliance is also hosted on the external, IP-based storage.
Verify that an SFTP server is available to store file-based backup data.