Why does adb return offline after the device strin

问题:

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

回答1:

Try the following:

1. Unplug the usb and plug it back again.

2. Go to the Settings -> Applications -> Development of your device and uncheck the USB debugging mode and then check it back again.

3. Restart the adb on your PC. adb kill-server and then adb start-server

4. Restart your device and try again.

回答2:

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.

回答3:

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.

回答4:

I've had a similar issue with one of my phones. I was unable to connect and use usb debugging on any of my computers. In the end, I had to restart the usb debugging on the phone manually [doing so using the Developer menu was not enough].

There's only one command you have to run on your phone [I did it using Terminal Emulator app]:

adb usb

And that was it.

Hope this helps someone in the future.

回答5:

You may also try downloading newest version of adb http://developer.android.com/tools/help/adb.html

回答6:

 adb kill-server
 adb start-server

that solved my problem

回答7:

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

回答8:

On my Galaxy Nexus with Android 4.2.2, I had the same problem initially, 'adb devices' was showing the device but with offline status (USB debugging was initially active on my device).

These are the steps I took to remedy the situation :

1. Disable USB debugging (Device not connected to PC)
2. Re enable USB debugging
3. Now connect to your PC, now a pop up on the device (not on PC) will ask you for authenticating the PC, Thats it...

adb devices now lists both device id and no offline.

回答9:

For me with Android 4.1.1 only rebooting device works

回答10:

I post here my question just in case is helpful for somebody else. My problem was that my colleague was connected to the same device and I was not able to connect to the same device.

Note: I had this problem with Amazon Fire TV connecting over Wifi.

There are 2 solutions:

Easy to "drop" his connection (sorry buddy :)

Restart the device
adb kill-server
adb start-server
adb connect device-ip

A bit more difficult but two clients can use the same device (use different TCP ports)

Please look at this answer

回答11:

Run SDk Manager and install Android SDK Tools and Android SDK Platform-tools updates. ADB must be updated to a new version for 4.2.x

回答12:

I had the same issue and none of the other answers worked. It seems to occur frequently when you connect to the device using the wifi mode (running command 'adb tcpip 5555'). I found this solution, its sort of a workaround but it does work.

1. Disconnect the usb (or turn off devices wifi if your connected over wifi)
2. Close eclipse/other IDE
3. Check your running programs for adb.exe (Task manager in Windows). If its running, Terminate it.
4. Restart your android device
5. After your device restarts, connect it via USB and run 'adb devices'. This should start the adb daemon. And you should see your device online again.

This process is a little lengthy but its the only one that has worked everytime for me.

回答13:

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 

回答14:

1. make sure the device is set for usb debugging
2. Have the adb client running (e.g. via "adb usb" or adb start-server"
3. LEAVE the device connected via usb!!!
4. AND THEN reboot the device.

This always brings my Motorola MB525 "online" again, after adb complains it would be "offline". I'm using OSX btw.

回答15:

I made adb working on Android 4.4.2 with GT-N8010 (Samsung tablet) after setting device in authorized mode once upgraded adb to SDK version.

~/local/opt/Android/Sdk/platform-tools/adb
Android Debug Bridge version 1.0.32

While It did not work using :

adb version   
Android Debug Bridge version 1.0.31

Shiped in Ubuntu LTS version :

apt-cache show android-tools-adb  | grep Version
Version: 4.2.2+git20130218-3ubuntu23

This link may help then

Can't connect Nexus 4 to adb: unauthorized

回答16:

After wasting hours on it, I have updated my version of adb and now adb devices shows my device online and I can run the app on it again.

回答17:

also make sure adb isn't running in your processes automatically. If it's there right click open file location, figure out what is starting it, kill it with fire. Run the updated adb from an updated android sdk platform tools. This was the issue with mine, hope it helps someone.

回答18:

What did me in is was that multiple unrelated software packages just happened to install adb.exe -- in particular for me (on Windoze), the phone OEM driver installation package "helpfully" also installed adb.exe into C:\windows, and this directory appears in %PATH% long before the platform-tools directory of my android SDK. Unsurprisingly, the adb.exe included in the phone OEM driver package is MUCH older than the one in the updated android sdk. So adb worked just fine for me until one day something caused me to update the windows drivers for my phone. Once I did that, absolutely NOTHING would make my phone status change from "offline" -- but the problem had nothing to do with the driver. It was simply that the driver package had installed a different adb.exe - and a MUCH older one - into a directory with higher precedence. To fix my installation I simply altered the PATH environment variable to make the sdk's adb.exe have priority. A quick check suggested to me that "lots" of different packages include adb.exe, so be careful not to insert an older one into your toolchain unintentionally.

I must really be getting old: I don't ever remember such a stupid issue taking so endlessly long to uncover.

回答19:

Check that the ADB version that you are running is newer than the version of the OS on the connected devices. For me, updating the ADB helped to get the device online.