How to fix alarm not going off?

[Adrian Abaja]

As a student really depend on my phone on waking up in the morning so I always set an alarm on it everyday. About a year ago, when my phone was new I really have no problems about the 'clock' app built in it but then this year it wouldn't go off almost all the alarm I've set. I have been clearing its cache, and it worked but then after some time it won't go off again. I dont like downloading third party clock apps because I only have limited storage. Any fix?

 

[Chris5483]

What phone and version of Android? While I don't think this would be a concern, for a system app, if you have marshmallow or nougat maybe the phone is putting that app to sleep to save battery?