This error is fully recoverable.   

If you do not have a job running.  
1) Open the top of the printer.   
    Ensure the printbar is positioned over the maintenance tray. 
2) Re-initialise the printer using the Settings/Power menu restart item.  

If you do have a job running. 
1) Open the top of the printer. 
    Cut the paper but do not remove the job.
    Ensure the printbar is positioned over the maintenance tray. 
2) Restart the printer using the Settings/Power menu. 
3) Resume your job by pressing Print.  

The error occurs typically due to a print head maintenance routine that runs autonomously when the 2D print bar has been idle for a long period.