I recently updated to Android Studio 2.3, and now when I try to run the application, the emulator does not come online. It times out after 300 seconds.
Additionally,
Once again, please wait for a while, sometimes you missed that it actually worked but you are feeling really stressed and could not wait(I was).
Not sure why I fixed the same issue that happened on my Macbook, however, choose Nexus 5X API R would work somehow. OR below
Wipe Data: Tools->Open AVD Manager and click ▼ the emu "Wipe Data"
Cold Boots Now: Tools->Open AVD Manager and click ▼ the emu "Cold Boots Now"
Uninstall & Reinstall Android Emulator from SDK: Tools->Open SDK Manager->Android SDK(left-side menu)->SDK tools(middle in the main screen), then click "Android Emulator" and APPLY, then again click "Android Emulator" apply to reinstall, so finish