Samsung (Galaxy S4) does not show Authorize USB debugging dialog box I am trying to follow the instructions here, but my phone never displays the "Authorize USB Debugging" option.

On the PC side, adb devices shows that the PC see the device, but it is listed as "offline" and I cannot use adb shell to talk to it.

Moreoever, if I unplug the device, adb devices does not list it at all, so I assume that the adb server is able to see the phone and simply cannot talk to it.

How can I force the "Allow USB Debugging" to appear on the phone?

I have already tried restarting both devices and disabling and enabling USB debugging on the phone.
I have had this happen multiple times on multiple Android devices. Solved every time by putting the device in Photo transfer (PTP) mode.

ADB will not work for me when my device is in MTP or any other mode.