Are you requesting storage permission at `runtime`? Even if you add uses-permission in manifest, still you need to ask user to grant permissions at runtime. Here is code:
/ Storage Permissions private static final int REQUEST_EXTERNAL_STORAGE = 1; private static String[] PERMISSIONS_STORAGE = { Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE }; /** * Checks if the app has permission to write to device storage * * If the app does not has permission then the user will be prompted to grant permissions * * @param activity */ public static void verifyStoragePermissions(Activity activity) { // Check if we have write permission int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE); if (permission != PackageManager.PERMISSION_GRANTED) { // We don't have permission so prompt the user ActivityCompat.requestPermissions( activity, PERMISSIONS_STORAGE, REQUEST_EXTERNAL_STORAGE ); } }
Read more about the runtime permission request here: https://developer.android.com/training/permissions/requesting.html

For API 23+ you need to request the read/write permissions even if they are already in your manifest.
// Storage Permissions private static final int REQUEST_EXTERNAL_STORAGE = 1; private static String[] PERMISSIONS_STORAGE = { Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE }; /** * Checks if the app has permission to write to device storage * * If the app does not has permission then the user will be prompted to grant permissions * * @param activity */ public static void verifyStoragePermissions(Activity activity) { // Check if we have write permission int permission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE); if (permission != PackageManager.PERMISSION_GRANTED) { // We don't have permission so prompt the user ActivityCompat.requestPermissions( activity, PERMISSIONS_STORAGE, REQUEST_EXTERNAL_STORAGE ); } }
AndroidManifest.xml
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
For official documentation about requesting permissions for API 23+, check https://developer.android.com/training/permissions/requesting.html