Access to usb key an file navigation from old app


I “upgraded” a galaxy note II to e os 0.11 (from android 4.12 to 7.1.2). Since that, the usb key doesn’t appear under /storage so it’s impossible to access it from this app and it’s difficult to navigate throught file because the /emulated and some other directories doesn’t show it content anymore.

How i can fix that ? i already tried to do chmod a+r /emulated while being root, but this does nothing on this folder, i can’t change it’s right. I don’t even have an error message (WTF ?)