How to resolve the "ADB server didn't ACK" error? [duplicate]

Question

Try the following:

• Close Eclipse.
• Restart your phone.
• End adb.exe process in Task Manager (Windows). In Mac, force close in Activity Monitor.
• Issue kill and start command in \platform-tools\
  • C:\sdk\platform-tools>adb kill-server
  • C:\sdk\platform-tools>adb start-server
• If it says something like 'started successfully', you are good.

For anyone using OSX (I'm aware OP isn't): What worked for me in the end was removing the android settings folder in the home directory.

rm -Rf ~/.android

For me it didn't work , it was related to a path problem happened after android studio 2.0 preview 1, I needed to update genymotion and virtual box, and apparently they tried to use same port for adb.

Solution is explained here link! Basically you just need to:

1) open genymotion settings

2) specify sdk path for the adb manually

3) adb kill-server

4) adb start-server

Similar questions are

• "The connection to adb is down, and a severe error has occured."
• The connection to adb is down, and a severe error has occured.You must restart adb and Eclipse.Please ensure that adb is correctly located
• ECLIPSE-The connection to adb is down, and a severe error has occured

First close IDE.

In my case I killed adb via Task Manager(adb kill-server did not work)
then adb start-server

• daemon not running. starting it now on port 5037 *
• daemon started successfully *

If you see "started successfully" than it is solved, now start IDE.

On my Mac, I wrote this code in my Terminal:

xxx-MacBook-Pro:~ xxx$ cd /Users/xxx/Documents/0_Software/adt20140702/sdk/platform-tools/

xxx-MacBook-Pro:platform-tools xxx$ ./adb kill-server

xxx-MacBook-Pro:platform-tools xxx$ ./adb start-server

• daemon not running. starting it now on port 5037 *
• daemon started successfully *

xxx-MacBook-Pro:platform-tools tuananh$

Hope this help.