Android Studio Debugger Port Error - "handshake failed - connection prematurely closed"

When I try to attach the Android Studio Debugger to a process, I get the following error:

Error running Android Debugger (8603):
Unable to open debugger port (localhost:8603): java.io.IOException "handshake failed - connection prematurally closed"

Kudos to whoever spelled prematurely that way. Anyway, how do I get around this problem?

I'm using Android Studio 1.2.2 on Ubuntu. This did not help.

The best and one solution for me was just to restart Android Studio.

Before I tried to restart adb server from command prompt or disable and enable adb integration from tools->Android->Check/Unchek the line, unplug and plug device , but nothing helped.

For me these didnt work: Restart Android Studio,adb kill start server, restart phone.

Worked for me: Tools->Android->Disable and Enabled ADB Integration.

On Windows, restarting Android Studio didn't work. I instead killed the "adb.exe" process then retried.

I didn't need to restart my device, only restarting android studio fixed it ( clean your project if needed).

If doesn't work then restart your device.

Maybe you should consider retaining only one device or a emulator, because Android Studio or Intellij IDEA only accept one device or emulator when debugging. It works well for me. I hope this can help.

Restarting the ADB server worked for me:

$ adb kill-server

$ adb start-server
* daemon not running. starting it now at tcp:5037 *
* daemon started successfully *

$ adb devices 
List of devices attached 
ce0217127216c0220c	device

I had to restart both my android device and android studio. That seemed to work for me.

In my case, often the reason is bad USB cable. Just replace another, better USB cable will work.

It shows that your previous debbugger was not closed. You should click stop (red button) to stop your attach previously, and rerun your debbugger. It would attach again