This error is usually because of having one of the I/O cards disconnected from the PLC.
If you don't want the PLC to go to the stop mode when this happens, you can create OB86 in your PLC program and download it to the PLC.
You don't need to write any PLC program in the OB86. Just an empty OB86 will do the trick.
After you download OB86 into the PLC, next time that this error happens, the PLC won't go to the stop mode. Only the "system fault" LED will be turned on so that you know there is an error in the system and you need to do something about it.