After updating my nexus 4 to new android 5 (lollipop) when i open an apk file, the install button not working!! Also i checked unknown source in my device settings.

What the problem? please help :(

marked as duplicate by bmdixon, Dan Hulme, Izzy, eldarerathis Dec 1 '14 at 1:20

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I have used lux lite application, this application set display brighness for reading in night mode. my problem solved when i unistall this app.


This happens when you have apps that interfere with the installation.
Example: I used to have Avast on my phone. Every now and then I couldn't install an app for the problem you're describing.
I uninstalled Avast (but just disabling it would be fine) and everything went fine.
So this is it: look at the apps already installed in your phone. Chances are there is something that blocks the installation...

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