How do you fix 3110cn laser printer Error code 077-901?

Error code 077-901 on the 3110cn laser printer typically indicates a problem with the imaging unit or the toner cartridge. To fix this, first, power off the printer and check that all toner cartridges are properly seated and not empty. If the cartridges are fine, consider replacing the imaging unit, as it may be worn or defective. After making any necessary changes, power the printer back on and see if the error persists.