Front camera not working after a while, issue with Smart Lock This is basically the same issue as described here:

Camera isn&#39;t available - Trusted Face ( Android Lollipop - Nexus 5)

Im running Marshmallow on a Nexus 5.

So yesterday i enabled password protection and Smart Lock with "Trusted Face".
This worked great so far.

However, after some time (like 4-8 hours) the front camera will stop working.
This will cause Smart Lock to not recognize me obviuosly and i have to use my password every time.

When launching the camera app, i am able to use the back camera, however switching to front only gives me a black screen and the app does not react to input anymore.

Rebooting the device will fix this, until it starts againt after the mentioned time-span.

Anyone got any ideas?

EDIT:
Clearing the cache (as advised in an answer) did prolong the time the front camera worked to about 36 hours but did not fix this permanently.
I had issues with my nexus 5 front camera not working randomly (switching to front camera would give a blank screen). wiping cache fixed it. I suggest you try it.