I bought a new external drive and connected it.
When I look in storage > disks I can see the drive.
I've gone into storage > file systems and clicked on create | mount, selected create, selected the drive (type is set to ext4) and clicked save.
When I reboot the system, I can create a partition, but when I try to mount it I'm getting this message.
I'm not sure what I'm doing wrong with adding this drive.