Android Studio ADB connection error

You need to kill the adb process that is running, to do so,

1. Go to Spotlight search, open Activity Monitor,

2. Loop for adb under CPU tag,

3. Now Select it and Force Quit the process.

You can kill adb process through Terminal command too, by simply typing Kill -9 adb

Note: Sometimes When u tried to force close them they kept restarting. Make sure you quit any emulators and disconnect any devices to avoid any mistake.

I spent around a complete day to look for the solution but couldn't find an exact one. Finally what i did was that I uninstalled my antivirus and after that it worked like a charm. So, here I shortlist the steps to check whether you are solving for the correct problem or not:-

1. Run command prompt and set path to where adb.exe file is present. (In most of the cases it's found at C:\Users\YOUR_USERNAME\AppData\Local\Android\Sdk\platform-tools)
2. Type adb start-server and press enter.
3. If there is an error displayed saying something like "Cannot connect to daemon" , then you must look in your antivirus for firewall settings and add the path to its exceptions or you can simply uninstall your antivirus.