Emulator not starting after updating to Android Studio

I had the same problem. All I did to solve it was updating Android Emulator and Intel x86 Emulator Accelerator under Android SDK Manager > SDK Tools. It started to work again.

Official Solution from Google issue tracker.

SOLUTION A

HVF Solution: Running the emulator on Canary channel 26.1.x (API 25/26 recommended) with Hypervisor.Framework I implemented this solution and it worked. I am using emulator now on macOS High Sierra.

A1 - If HAXM installed in Android Studio, uninstall it;

• Go to SDK Manager > SDK Tools (or Appearance & Behaviour > System Settings > Android SDK)
• Uncheck Intel x86 Emulator Accelerator (HAXM Installer) and Apply. This will uninstall HAXM.

A2 - You might need to first install HAXM in order to get HVF to work.

• Install standalone Intel HAXM as a regular .dmg install. Download from here: https://software.intel.com/en-us/articles/intel-hardware-accelerated-execution-manager-intel-haxm

• HAXM on OS X keeps on disappearing. For any reason, you can uninstall standalone HAXM installation by

  sudo Library/Extensions/intelhaxm.kext/Contents/Resources/uninstall.sh

• If above not work.Try

  sudo System/Library/Extensions/intelhaxm.kext/Contents/Resources/uninstall.sh

A3 - Check whether your macOS supports Hypervisor.Framework or not:

• $ sysctl kern.hv_support

  kern.hv_support: 1 (if support =1, if not support = 0) (should support to implement HVF solution)

A4 - Find the file "advancedFeatures.ini". It may be placed in;

• ~/.android/advancedFeatures.ini ( Users/<username>/.android/advancedFeatures.ini) or
• /Users/<username>/Library/Android/sdk/emulator/lib/advancedFeatures.ini (I found mine here)

A5 - Open "advancedFeatures.ini" with an editor.

• Find the line HVF = off. Change off to on; "HVF = on"

A6 - Restart Android Studio if it is open (Restart the computer if necessary). Create and RUN the emulator :) No more HAXM warnings :)

SOLUTION B

I didn't try this solution but several comments claim that it also worked. You can try this also, follow the instructions from here : https://blog.celogeek.com/201708/672/android-studio-emulator-haxm-on-mac-os-high-serria-10-13/