Panasonic KX-TD500 System Reference Manual page 1114

Error Message No.
141 Attempting to remove an extension or trunk port
which is registered in Power Failure Transfer
(PFT) assignment.
150 Impossible to change the Numbering Plan to
"Fixed," because there exist DN's which should
be blank in the "Fixed" mode in the Hundred
Block.
160 Impossible to change UCD/Paging group, for
the pickup group belonging to the UCD/Paging
group contains extensions.
170 When the XDP port status is in OUS or in INS,
changing the XDP mode from "On" to "Off" is
impossible.
Probable Cause
10-K-6
Countermeasure
Cancel the assignment of the corresponding
card, and then delete the port.
Clear DN's which should be blank.
Change after deleting all the extensions in
the pickup group.
Change after removing the XDP port.