Android Launch! The connection to adb is down, and a severe error has occured

If you get this error, when you try to launch your Android app on Emulator device, then simply try the following troubleshooting steps.

1. Close you Eclipse IDE
2. Locate your adb tool (you may simple find the path from the error logs)
3. Now open Command Prompt/Terminal depending on if you are on Mac OS X or Windows.
4. Execute command adb kill-server
5. Now Open Eclipse IDE again and try running you app, there should be no issue.

If you still facing the issue, then it may be that ADB process is was not killed properly.

For Windows,

1. Close Eclipse IDE.
2. Go to task manager (ctrl+alt+del)
3. Look for adb.exe
4. Terminate/End the process.
5. Now Open eclipse and launch AVD.

For Mac OS X,

1. Close Eclipse IDE.
2. Open Activity Monitor from Spotlight
3. Under Cpu tab, look if eclipse/adb process is running
4. Double Click on the Process name and Exit it.
5. Restart Android Eclipse IDE and run AVD again

Other Solutions :

Check the adb.exe location if it has been moved from android-sdk-windows/tools/adb.exe to android-sdk-windows/platform-tool/adb.exe. If yes, replace it to /tools/ folder.

If still things are the same, try restarting your system.

[2014-08-28 12:49:43 - SDK Manager] Created AVD 'avd2.3' based on Android 2.3.3, Intel Atom (x86) processor,
[2014-08-28 12:49:43 - SDK Manager] with the following hardware config:
[2014-08-28 12:49:43 - SDK Manager] disk.dataPartition.size=200M
[2014-08-28 12:49:43 - SDK Manager] hw.accelerometer=yes
[2014-08-28 12:49:43 - SDK Manager] hw.audioInput=yes
[2014-08-28 12:49:43 - SDK Manager] hw.battery=no
[2014-08-28 12:49:43 - SDK Manager] hw.camera.back=none
[2014-08-28 12:49:43 - SDK Manager] hw.camera.front=none
[2014-08-28 12:49:43 - SDK Manager] hw.dPad=no
[2014-08-28 12:49:43 - SDK Manager] hw.device.hash2=MD5:e4aa1843c10fc4d1028
[2014-08-28 12:49:43 - SDK Manager] hw.device.manufacturer=Google
[2014-08-28 12:49:43 - SDK Manager] hw.device.name=Nexus S
[2014-08-28 12:49:43 - SDK Manager] hw.gps=yes
[2014-08-28 12:49:43 - SDK Manager] hw.keyboard=yes
[2014-08-28 12:49:43 - SDK Manager] hw.lcd.density=240
[2014-08-28 12:49:43 - SDK Manager] hw.mainKeys=yes
[2014-08-28 12:49:43 - SDK Manager] hw.ramSize=512
[2014-08-28 12:49:43 - SDK Manager] hw.sdCard=yes
[2014-08-28 12:49:43 - SDK Manager] hw.sensors.orientation=yes
[2014-08-28 12:49:43 - SDK Manager] hw.sensors.proximity=yes
[2014-08-28 12:49:43 - SDK Manager] hw.trackBall=no
[2014-08-28 12:49:43 - SDK Manager] skin.dynamic=no
[2014-08-28 12:49:43 - SDK Manager] vm.heapSize=32

[2014-08-28 12:49:52 - Code2careDemo] ------------------------------
[2014-08-28 12:49:52 - Code2careDemo] Android Launch!
[2014-08-28 12:49:52 - Code2careDemo] The connection to ADB is down, and a severe error has occurred.
[2014-08-28 12:49:52 - Code2careDemo] You must restart adb and Eclipse.
[2014-08-28 12:49:52 - Code2careDemo] Please ensure that adb is correctly located at '/Users/c2c/Android/adt-bundle-
mac-x86_64-20140702/sdk/platform-tools/adb' and can be executed.