Canon imageCLASS MF4690 Operation Manual page 244

Message
USB/USB PORT ERROR
TURN POWER OFF → ON
Description
A USB memory error or
USB memory port error has
occurred.
Action
Disconnect the USB memory
from the USB memory port,
turn off/on the main power
switch, and connect the USB
memory again. If the message
appears after connecting
the USB memory to the USB
memory port, the USB memory
may have problem. If the
message persists after turning
on the main power switch, the
USB memory port may have
problem. In this case, turn
off the main power switch,
disconnect the power cord,
and contact Canon Customer
Care Center.
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