Run 'zpool import' to list which pool cannot be imported:

# zpool import
  pool: test
    id: 13783646421373024673
 state: FAULTED
status: One or more devices are missing from the system.
action: The pool cannot be imported.  Attach the missing
	devices and try again.
   see: https://zfsonlinux.com/msg/ZFS-8000-6X
config:

        test              FAULTED   missing device
          c0t0d0          ONLINE

        Additional devices are known to be part of this pool, though their
        exact configuration cannot be determined.

ZFS attempts to store enough configuration data on the devices such that the configuration is recoverable from any subset of devices. In some cases, particularly when an entire toplevel virtual device is not attached to the system, ZFS will be unable to determine the complete configuration. It will always detect that these devices are missing, even if it cannot identify all of the devices.

The pool cannot be imported until the unknown missing device is attached to the system. If the device has been made available in an alternate location, use the '-d' option to 'zpool import' to search for devices in a different directory. If the missing device is unavailable, then the pool cannot be imported.