HP says that the error 50.00.19 and 50.00.22 come frome defective scanner/laser from one of the colors CMYK and that it can be fixed by turning the printer off and then on or check the scanner/laser connector or replace the defective scanner/laser.
From our tests most of the time this error came from a defective toner cartridge. So quick solution to this problem is to replace the toner cartridge sometimes can solve these errors. Usually the Cyan or Yellow cartridge can cause these two errors (mainly on HP Color Laser M551 Enterprise Printers).
If this will not solve the problem then take out all the toner cartridges and clean the inside of printer, especially the laser reflector lens. Also open the back of the printer and take out the laser scanner and heater and clean everything, small toner particles usually remains on the laser reflector lens and block it’s operation.