Lexmark MX822
650.84 error message is prompted on the printer control panel when printing in duplex.
Turn off the printer for at least a minute and turn it back on again.
Print a document in duplex and check if the error message still appears.
If the issue remains, restart the print job.
Contact Lexmark support if this issue still occurs after second duplex test print.
Lexmark CX82x/86x, MX72/82: 843.00 Scanner Error Message
The printer displays any of these error codes on the control panel: 43.40P, 43.40Q, 43.40R, 43.40S, 43.40T, 43.40U, 43.40V, 43.40W, 43.40X, 43.40Y or 43.40Z