If you have a Samsung phone or tablet, and you have installed the “Samsung Kies”, you will unable to use the Android File Transfer application. You probably got the following error message:
“Can’t access device storage. If your device’s screen is locked, disconnect its USB cable, unlock your screen, and then reconnect the USB cable.”
When you read this message, you might follow the instruction and did it several time, but the connecting doesn’t work. the problem was Samsung Kies! That’s right! The Samsung Kies software is the key to solve your problem. Uninstalling Samsung Kies is the only work around for this issue. Even if you’ve never installed Kies on your Mac, the driver may still be on your Mac blocking Android file transfer. So, what to do?
1. Unplug your Android device
2. Download the Kies Installer. launch it, and take the official UNINSTALLER!
3. Click “Uninstall”
4. Reboot your computer
5. Connect your android device to computer, then when you see the little USB status symbol swipe the status bar down (or access it however your Android version requires) and you should see the message “Connected as a media device. Touch for other USB options.”
6. Touch for other USB options, and then make sure Media device (MTP) is checked.
Now you should be able to connect your phone or tablet with Android File Transfer (for Mac). Cheers!