UPDATE 2017.08.03: This should be fixed with the release of HAXM 6.1.1. Make sure you’re running the latest version of Android Studio
On a recent project I was working on, I wasn’t able to start the Android Emulator/Simulator anymore from within Android Studio. It would launch, but then – without any errors or warnings – close all by itself.
Upon launching the Android Emulator from the Command Line I finally got an error visible:
$ cd $(dirname $(which emulator)) && ./emulator -avd Nexus_5X_API_25 emulator: WARNING: encryption is off Hax is enabled Hax ram_size 0x60000000 HAX is working and emulator runs in fast virt mode. Failed to sync vcpu reg Failed to sync vcpu reg Failed to sync vcpu reg Failed to sync vcpu reg Failed to sync vcpu reg Failed to sync HAX vcpu contextInternal error: Initial hax sync failed
One Google Search Coupon later it turns out the thing preventing the emulator from running was “that other thing using vcpu’s” …
👉 Killing docker will let you run the Android Emulator without any problems.
I haven’t tested other suggested solutions (such as tweaking the settings of the virtual device), but at least this one did it for me.