Examine command output, debug logs, and system logs for a more detailed message on the error.

Do not try to manually assign any volumes that are already assigned, because it is not valid except for one condition: you can assign volumes for NetBackup catalog backups if the volume is already assigned for NetBackup catalog backups. Always use barcodes that are unique in the six least significant characters, across all media in all robots. Or use media ID generation rules to ensure that unique media IDs are generated in a robot inventory update.