Panasonic KX-T336 System Reference Manual page 1288

DATA ERROR No.
Attempting to remove a card which is registered
431
in Power Failure Transfer (PFT) assignment.
Impossible to change the Numbering Plan to
"Fixed," because there exist DN's which should
440
be blank in the "Fixed" mode in the Hundred
Block.
450 Impossible to change ICM/Paging group, for the
pickup group belonging to the ICM/Paging group
contains extensions.
Probable Cause
10-D-5-1 10-D-6
(70695) (21292)
Countermeasure
Cancel the PFT assignment of the card.
Clear DN's which should be blank.
Change after deleting all the extensions in the
pickup group.