A Qlik system or platform may crash for different reasons. Therefore, there is no specific part where I can tell you the reason or root cause of the crash, but you can start with certain actions to be able to investigate the root cause.
1. Validate if the services are running correctly. You must validate this in the operating system's services console. 2. In case a service is not running or has crashed, you can check in the Windows event viewer the reason why it crashed or if it was due to something external. 3. Check the logs of the service(s) that were not running, to see what error message may be being recorded. 4. Investigate the error message that may appear in the Windows events or Qlik Sense logs. You can do this on Google or directly in the Qlik Community.
I hope these tips are helpful in finding the cause of your problem.
Keep in mind that the first thing check is if there were any power outages in your server room or if there was a problem in your vApp cloud (whichever applies to you).
Then use the above logs to check for possible root causes after eliminating 'hardware' / 'vApp' cloud for issues.
Some possible causes to consider:
Windows update problems.
Maxed out RAM and or CPU issues causing system failure (Check windows event logs).
