ADB not responding. You can wait more,or kill "adb.exe" process manually and click 'Restart'

Go to

Tools > Android > (Uncheck) Enable ADB Integration (if studio hangs/gets stuck end adb process manually)

then,

Tools > Android > (Check) Enable ADB Integration

On my macbook pro, i was occasionally getting this in Android Studio. The following resolved it for me:

Open up a Terminal and, instead of using 'adb kill-server', use this:

$ killall adb

wait a minute and it looks like Android Studio automatically restarts adb on it's own.

From the command prompt run the command adb kill-server. This will shutdown ADB and android studio or Eclipse if you were to use that, would show Waiting for ADB as you said.

Once ADB has shutdown down run adb start-server or run adb devices which will automatically start the adb service and show that your android emulator or development devices has successfully connected.

If you are suffering from "ADB not responding. If you’d like to retry, then please manually kill ‘adb’ and click ‘Restart’ or terminal appear Syntax error: “)” unexpected" then perhaps you are using 32bit OS and platform-tools has updated up 23.1. The solution is to go back to the platform-tools 23.0.1.

You can download the platform-tools 23.0.1 for Linux here , for windowns here and Mac here

After the download, go to your sdk location > platform-tools folder to delete old platform-tools in sdk and paste down into the downloaded one.

Woohooo ... it should work.

This is a bug with latest ADT.

For me, on Windows 7, killing the ADB server and restarting it via command line did not help. It would not start up successfully.

>adb kill-server

>adb start-server
* daemon not running. starting it now on port 5037 *
ADB server didn't ACK
* failed to start daemon *

So killing the adb.exe process via Task Manager was actually the easiest solution that case.