Emulator: emulator: ERROR: AdbHostServer.cpp:102: Unable to connect to adb daemon on port: 5037

This is likely caused by insufficient permissions. Run Android Studio or your command prompt (whichever you prefer) as an administrator and that should solve your problem.

1. emulator -list-avds
2. adb start-server 
3. emulator -avd <avd_name>

if you see PANIC: Missing emulator engine program for 'x86' CPU.

then you can try

1. emulator -list-avds
2. adb start-server
3. $ANDROID_HOME/emulator/emulator @name_device

for cold boot use flags -no-snapshot and -no-snapshot-load

I had the same error as yours. I fixed it by updating everything in Android Studio, including the SDKs. After that, I wipe the data on my emulator and run the program. It works like a charm, hopefully you can fix yours, too.