If you are getting this error code on a printer then it means that your are using the wrong print driver. !R!SEM6;EXIT; is a command used by kyocera printers and copiers.
!R! stands for the recognation code for prescribe commands.
SEM stands for Set Emulation Mode
this command temporary changes the emulation mode
The 6 means HPIII emulation
EXIT ends the execution
If your printer or copier outputs this then the driver you are using is the wrong driver or you have an issue with your emulation. If you have an issue with your emulation then you have to go into preferences and properties of the driver and change it. If its the driver then use a different driver or printer.