Why does adb return offline after the device strin

Question

I use "adb devices" to get following result. Only one device is connected to PC by USB, but we get 8 lines of result.

Could anyone suggest the reason?

WH96TNE00361    offline
WH96TNE00361    offline
WH96TNE00361    offline
WH96TNE00361    offline
WH96TNE00361    offline
WH96TNE00361    offline
WH96TNE00361    offline
WH96TNE00361    offline

Answer 1

Beginning from Android 4.2.2, you must confirm on your device that it is being attached to a trusted computer. It will work with adb version 1.0.31 and above.

Answer 2

For me with Android 4.1.1 only rebooting device works

Answer 3

Had this on client's machine it turned out he had an out of date version of adb installed via website offering adb and fastboot. The client in question didn't want to install the whole SDK because of perceived bloat :S .

So if you're seeing offline make sure you've downloaded and using the latest adb. I ended up emailing him adb executable.

Also worth checking that the adb you are using is the correct one in the Path. i.e on Mac

$ which adb
/Users/me/dev/adt-bundle-mac-x86_64/sdk-macosx/platform-tools/adb 

Answer 4

To complete the previous answers, another possible solution is to change the USB socket in which your cable is plugged in.

I had this problem (with the classical answer about using adb kill-server / start-server not working) and it solved it.

Actually, it took some time to find that because Windows was correctly recognizing the device in my first socket. But not ADB. As Windows was recognizing the device, I had no real need to test other USB physical sockets. I should have.

So you can try to plug the cable in all your USB physical sockets directly available on your computer. It did worked for me. Sometimes the USB sockets are not managed the same way by a computer.

Answer 5

 adb kill-server
 adb start-server

that solved my problem

Answer 6

Reboot the device. This always fixes it on Mac OS, whereas adb kill-server does not.