Recommended way to migrate my main pool from RAID1 (2 disks) to RAIDZ1 (4 disks)

So I’m stuck. It says “Error in Apps Service” and it says "Application(s) have failed to start:
Command ‘(‘mount’, ‘-t’, ‘zfs’, ‘main/ix-applications/k3s/kubelet’, ‘/var/lib/kubelet’)’ returned non-zero exit status 1.

Doing this manually fails:

root@truenas[~stk]# mount -t zfs main/ix-applications/k3s/kubelet /var/lib/kubelet
filesystem 'main/ix-applications/k3s/kubelet' cannot be mounted using 'mount'.
Use 'zfs set mountpoint=legacy' or 'zfs mount main/ix-applications/k3s/kubelet'.
See zfs(8) for more information.
root@truenas[~stk]#