Hope this helps
I have also added the fix that I applied for the similar issue in above thread. Let me add that here as well if that helps.
1. Open task manager.
2. Locate if any QV.exe process running through the same account (Nprinting Service Account) with which Nprinting Service is running.
3. Try to kill that process.
4. Restart Qlikview Nprinting Service.
5. Scheduled jobs should run fine now without the error.