Remove the toner cartridge, and then install a supported one to clear the message and continue printing. For more information, see the instruction sheet that came with the supply.
This error can also be caused by installing a genuine Lexmark cartridge, such as a high yield cartridge, that is not intended to be used in this product.
For more information, see Using genuine Lexmark parts and supplies.
Note: If you do not have a replacement cartridge, then see the “Ordering supplies” section or go to www.lexmark.com.