I can see my device in adb devices. It shows up as "offline". When it is "ready":

$ adb shell
$ su
# reboot

This would reboot my device. The exact problem is that my cellphone has been turning off on its own with no specific reason, so I was wondering if I could check the logcat to see the problem. I cannot start my device, I have to remove the battery and then start it, and when I do the log is empty... But my questions here are:

  • If adb can detect my device why can't it reboot it?
  • Why can't I turn on my android device from adb when I can reboot it?
  • What does offline mean: is it turned on or not? (when it isn't usually it doesn't even show in adb devices)
  • what offline means to a device?
    – hugemeow
    Commented Nov 20, 2012 at 12:05
  • @hugemeow That was the point of my question, but I did not get an answer... I still don't know what it is, but if you are getting this, there is something wrong. I flashed another ROM, and everything was OK again. I'm not sure what was causing it...
    – jadkik94
    Commented Nov 20, 2012 at 19:32
  • i am searching for this same thing - does it mean it thinks think the device is turned off? Commented Apr 16, 2015 at 16:12

2 Answers 2


I only encountered device shown via ADB as offline in two cases:

  • Device not authorized (ADB security features)
  • No proper udev rules setup

As the first case is most likely not your problem as these security features were not implemented in android when you asked this question. Your problem is most likely that you dont have proper udev rules.

You can fix this temporary bei starting adb on your computer as root:

adb kill-server; sudo $(which adb) start-server

or permanently by adding proper udev rules for your desired device vendor:

See https://wiki.cyanogenmod.org/w/UDEV for a collection of well-known vendors. if your vendor is not part of this you can add it by yourself. Plug the device via USB to your computer and check the output of: lsusb get the right vendorID of your device and add it to the udev rules file.

Also useful: http://developer.android.com/tools/device.html


"adb: offline" reason is generally because of usb cable. If you are not using your stock cable, try with another microusb cable..

Also, while it shows offline, try this: (not everytime but sometimes it helps)

adb kill-server
adb start-server
  • i am using the stock cable, and it's working fine(when my phone is "normal"). it shows the name of my device as offline when i run adb devices, only when it's in that state where i don't know if it's off or not... it shows in adb as offline (which means it is not off as usual) and anything i do with it shows it is off completely (and i cannot turn it on)... i will try kill/start server when my phone gets back in that state. thanks
    – jadkik94
    Commented Apr 8, 2012 at 21:54

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