T.2.3.4 Password entry is required during operation. (Have you set a password?)

Cause

A password has been set for the transfer operation.

Solution

Even if you forget the transfer password, you cannot cancel the password setting. You need to delete the password information.

Set the display unit to offline mode and initialize the memory.
M.17.5.1 Initialize Setting Guide - Initialize User Memory

When you forget the receive password
When you forget the receive password, you cannot receive files. Check if any backup files are saved in a location other than the display unit.