It is possible for the printer/MFP to display a 900 error code, to or hang during a duplex job, if the printer/MFP is in Quiet Mode.
Power off the printer/MFP and remove the paper tray.
Remove all media from the tray and adjust the right-hand tray guide back and forth until it is set on letter.
Reload the media in the tray and insert the tray into the printer/MFP.
Power on the machine and print the job that has been causing the error message.
Did the job print correctly?
Yes: The error is resolved.
Update the firmware with the latest version.
If the issue persists, contact Lexmark Technical Support.
If you need additional assistance, please see contact information. NOTE: When calling for service you will need to know your printer model type and serial number.
Please call from near the printer in case the technician asks you to perform a task involving the printer.