Canon PRISMAsync v3.2 Technical & Service Manual page 124

11504 Error Screen behaviour
NOTE
If the error is caused by a job on the system that cannot be printed, press the [Delete All Jobs]
button on the screen to remove the print jobs.
The [Delete all Jobs] button is only visible the second time a 11504 error occurs.
After all print jobs are deleted, the system will reboot and start up normally.
124 Chapter 10 - Troubleshooting
PRISMAsync V3.2