I'm trying to create a backup of a CT using a new PBS. The PBS Storage is shown correctly in the Proxmox interface, so I assume that I have entered the correct credentials, however when trying to run a manual backup to the PBS I get a 255 exit code (see below with personal details redacted for security):
INFO: starting new backup job: vzdump 102 --remove 0 --mode snapshot --node nodename --storage PBS
INFO: Starting Backup of VM 102 (lxc)
INFO: Backup started at 2020-09-16 18:30:48
INFO: status = stopped
INFO: backup mode: stop
INFO: ionice priority: 7
INFO: CT Name: test
INFO: including mount point rootfs ('/') in backup
INFO: creating Proxmox Backup Server archive 'ct/102/2020-09-16T17:30:48Z'
INFO: run: /usr/bin/proxmox-backup-client backup --crypt-mode=none pct.conf:/var/tmp/vzdumptmp41253/etc/vzdump/pct.conf fw.conf:/var/tmp/vzdumptmp41253/etc/vzdump/pct.fw root.pxar:/mnt/vzsnap0 --include-dev /mnt/vzsnap0/./ --skip-lost-and-found --backup-type ct --backup-id 102 --backup-time 1600277448 --repository root@pam@IPaddress:backup
INFO: Starting backup: ct/102/2020-09-16T17:30:48Z
INFO: Client name: nodename
INFO: Starting protocol: 2020-09-16T18:30:48+01:00
INFO: Error: parameter verification errors
INFO: parameter 'benchmark': schema does not allow additional properties.
ERROR: Backup of VM 102 failed - command '/usr/bin/proxmox-backup-client backup '--crypt-mode=none' pct.conf:/var/tmp/vzdumptmp41253/etc/vzdump/pct.conf fw.conf:/var/tmp/vzdumptmp41253/etc/vzdump/pct.fw root.pxar:/mnt/vzsnap0 --include-dev /mnt/vzsnap0/./ --skip-lost-and-found --backup-type ct --backup-id 102 --backup-time 1600277448 --repository root@pam@IPaddress:backup' failed: exit code 255
INFO: Failed at 2020-09-16 18:30:48
INFO: Backup job finished with errors
TASK ERROR: job errors
INFO: starting new backup job: vzdump 102 --remove 0 --mode snapshot --node nodename --storage PBS
INFO: Starting Backup of VM 102 (lxc)
INFO: Backup started at 2020-09-16 18:30:48
INFO: status = stopped
INFO: backup mode: stop
INFO: ionice priority: 7
INFO: CT Name: test
INFO: including mount point rootfs ('/') in backup
INFO: creating Proxmox Backup Server archive 'ct/102/2020-09-16T17:30:48Z'
INFO: run: /usr/bin/proxmox-backup-client backup --crypt-mode=none pct.conf:/var/tmp/vzdumptmp41253/etc/vzdump/pct.conf fw.conf:/var/tmp/vzdumptmp41253/etc/vzdump/pct.fw root.pxar:/mnt/vzsnap0 --include-dev /mnt/vzsnap0/./ --skip-lost-and-found --backup-type ct --backup-id 102 --backup-time 1600277448 --repository root@pam@IPaddress:backup
INFO: Starting backup: ct/102/2020-09-16T17:30:48Z
INFO: Client name: nodename
INFO: Starting protocol: 2020-09-16T18:30:48+01:00
INFO: Error: parameter verification errors
INFO: parameter 'benchmark': schema does not allow additional properties.
ERROR: Backup of VM 102 failed - command '/usr/bin/proxmox-backup-client backup '--crypt-mode=none' pct.conf:/var/tmp/vzdumptmp41253/etc/vzdump/pct.conf fw.conf:/var/tmp/vzdumptmp41253/etc/vzdump/pct.fw root.pxar:/mnt/vzsnap0 --include-dev /mnt/vzsnap0/./ --skip-lost-and-found --backup-type ct --backup-id 102 --backup-time 1600277448 --repository root@pam@IPaddress:backup' failed: exit code 255
INFO: Failed at 2020-09-16 18:30:48
INFO: Backup job finished with errors
TASK ERROR: job errors