About permissions issues with Android API 23 +

Beginning in Android 6.0 (API level), users grant permissions to apps while the app is running, not when they install T He app. This approach streamlines the app install process, since the user does not need to grant permissions when they install or Update the app. It also gives the user more control over the app ' s functionality; For example, a user could choose-give a camera app access to the camera and not the device location. The user can revoke the permissions at any time, by going to the app's Settings screen.

Http://developer.android.com/training/permissions/requesting.html

Real machine debugging when you want to open permissions in the settings

About permissions issues with Android API 23 +