I had the same problem. I tried using different apps, but still to no avail. Until I stumble upon OpenMTP and it says that my connection to the Android device is not working because an app is open and it is trying to connect to my device via USB, as well. Figured out that this app was Dropbox. I quit Dropbox, connected my Android phone and Android File Transfer opened like a charm.
Originally Posted by
walterkurtz i have tried multiple cables, multiple restarts, uninstalling/reinstalling android file transfer, open MTP and nothing works. i always get the same dialogue box stating "could not connect to device, try reconnecting or restarting your device."
add'l info: my phone is unlocked when i plug it in. i choose allow when it asks for access. and under usb settings, i've chosen usb controlled by this device and use usb for 'transferring files..'.
if anyone has solved this problem, please share. thank you!!