SOLVED Replaced Mainboard, now one encrypted disk can't be imported anymore.

[Spacemarine]

I'm stuck. I replaced my Mainboard because it wouldn't boot anymore, luckily I got it RMA. (ASROCK C2750D4L)

The system has 4 identical encrypted drives in a RaidZ-2 configuration. When I reconnected everyting, I forgot to connect one drive and booted the system. After I unlocked the pool with my password, I noticed that the pool is in a degraded state because one drive is missing. I rebootet and connected the missing drive. The drives are now connected in a different order to different ports, but I tink that should not be a problem?

However, one drive can't be imported anymore. I already rebooted several times and exchanged the order of the drives, the problem still persists.

Code:

[root@freenas-lti] ~# zpool status
  pool: LTI-storage
 state: DEGRADED
status: One or more devices could not be opened.  Sufficient replicas exist for
  the pool to continue functioning in a degraded state.
action: Attach the missing device and online it using 'zpool online'.
  see: http://illumos.org/msg/ZFS-8000-2Q
  scan: scrub repaired 0 in 3h11m with 0 errors on Sun Apr 23 03:11:08 2017
config:

  NAME  STATE  READ WRITE CKSUM
  LTI-storage  DEGRADED  0  0  0
  raidz1-0  DEGRADED  0  0  0
  gptid/feb5af1f-46af-11e6-9f27-d05099265226.eli  ONLINE  0  0  0
  4627256412628780505  UNAVAIL  0  0  0  was /dev/gptid/ff7cb0cf-46af-11e6-9f27-d05099265226.eli
  gptid/0043e383-46b0-11e6-9f27-d05099265226.eli  ONLINE  0  0  0
  gptid/0105311c-46b0-11e6-9f27-d05099265226.eli  ONLINE  0  0  0

errors: No known data errors

What is the problem here? And how can I solve it?
I'm not sure, if the drive that was missing, is the same drive that is now causing problems

 

[Stux]

Wipe the drive that can't be imported, then replace the missing drive with the now erased drive.

 

[Spacemarine]

I followed your advice, everything seems to work normally again, THANKS!

However, I wonder why these additional steps are neccessary?
http://doc.freenas.org/9.10/storage.html?highlight=replace drive#replacing-an-encrypted-drive
Why does everything have to be rekeyed?