Solving "adb server version doesn't match this client" error [duplicate]

I fixed this by doing the following:

1. going into GenyMotion settings -> ADB tab,
2. instead of Use Genymotion Android tools (default), I chose Use custom Android SDK Tools and then browsed to my installed SDK.

In my case the solution was this on an Ubuntu based OS:

adb kill-server
sudo cp ~/Android/Sdk/platform-tools/adb /usr/bin/adb
sudo chmod +x /usr/bin/adb
adb start-server

kudos: https://stackoverflow.com/a/38166059/3765109

One possible reason for the occurrence of this error is due to the difference in adb versions in the development machine and the connected connected device/emulator being used for debugging.

So resolution is:

1. Firstly disconnect device/emulator.

2. Run on terminal/command prompt following commands:

   adb kill-server
   adb start-server
   

This will start the adb successfully. Now you can connect device. Hope it helps.

It seems there are 2 adb version in your system. Please find them out and keep the adb in your Android SDK folder only, delete all others folders that including adb file. You can find out which adb you are using from Application Monitor:

It might be a problem if the adb is not the one in you Android SDK folder.

In my case, I found I was running adb from here:

/Library/Application Support/RSupport/Mobizen2

after deleting the Mobizen2 folder, then all adb commands work fine.