I am getting this error since two days ago when I updated my Android Studio to the latest stable version 2.3; the full error message I am getting from Gradle Console is:
07:59:59 E/adb: error: could not install *smartsocket* listener: Address already in use
07:59:59 E/adb: ADB server didn't ACK
07:59:59 E/adb: * failed to start daemon *
07:59:59 E/adb: error: cannot connect to daemon
07:59:59 E/ddms: '/Users/USER_NAME/Library/Android/sdk/platform-tools/adb start
server' failed -- run manually if necessary
My attempts to solve the issue:
- kill all - adbprocesses and make sure no process is holding port 5037,- adb kill-server(says- * server not running *even in cases when adb is running), close Android Studio, delete- ~/.androiddirectory, run- adb start-server(says- * daemon not running. starting it now at tcp:5037 *; * daemon started successfully *, start Android Studio and run application, MAC throws error- adb quit unexpectedlyand gradle console shows same the error I posted above.
- uninstalled and deleted all Android Studio stuff (except for projects directory), restarted MAC, installed fresh and latest android studio. 
- increased gradle vm ram - org.gradle.jvmargs=-Xmx1536Min project- gradle.properties
- uninstalled antivirus and restarted the mac 
Environment:
- OS: MacOS Sierra 10.12.3
- Android Studio: 2.3
- buildToolsVersion: '25.0.0'
- Android Debug Bridge version: 1.0.39
 
     
     
     
     
     
     
    