Android Emulator claims “WHPX is not configured”, crashes - android-emulator

The Android Emulator launched from Visual Studio 2019 for Xamarin development throws this message before launching:
WHPX is not configured
Turn on "Windows Hypervisor Platform" feature to switch to the Native Hypervisor and accelerate your emulator.
This is despite that Hyper-V is installed, according to the Microsoft documentation.
This is possibly related to the Emulator crashing after some time with no error message, or displaying this when launched from the Android Device Manager:
Please check if you can update your video driver.
If it doesn't help, try to Edit the AVD and set "hw.gpu.mode=off".
This is on a machine that used to run the emulator previously, just a fresh installation of Windows.

The error message is actually correct. On newer versions of Windows, “Windows Hypervisor Platform” (WHPX) is a separate feature on the Windows Features list.
Even the Microsoft docs have been updated to mention this. (Though it wasn't there when I was dealing with this problem and spent way too much time on it, sigh.)

Related

Android Studio: The emulator keeps crashing after sometime

Every time I run the emulator it runs normally at the beginning but after a couple of minutes it crashes and it's giving me this error:
emulator process finished with exit code 1073740791 (0xC0000409)
I am using windows 10 home edition. virtualization is enabled in bios. I don't have any other virtualization software installed (like virtual box).
any idea why this is happening?
It seems a buggy graphic card driver can cause a similar problem. I am not sure if this is generated your problem here or not, but it is worth to say; If you have an NVIDIA graphic card with the driver version of 378.49 (there may be other versions too!), you may experience this error due to some incompatibility with java.
Please update your graphic card driver or rollback it to version an older stable version and try again!. And read here for more information.
I might have an Idea what your problem is:
Restart the adb Server, you can do so by using the command Prompt in the following way:
First go to C/users/(YOUR USERNAME)/AppData/Local/Android/Sdk/platform-tools with the cd command.
Then just type adb kill-server, and adb start-server, so like this;
cd C/users/(YOUR USERNAME)/AppData/Local/Android/Sdk/platform-tools
adb kill-server
adb start-server
If that doesent work try to wipe and cold boot described in this question.
Try this :
Go to Tools ==> SDK Menager ==>Android SDK
(Appearance&Behavior=>System settings=>Android SDK)==>SDK Tools==>Intel x86 Emulator Accelerator(install this).
It will solve your problem.I hope it helps.
Here are a few things you can try:
Go to AVD manager and open settings for your virtual device. In the Emulated Performance section for graphics, change it from automatic to software.
Have a look at here. There could be an incompatability with other software incompatibility with other software such as Docker, Oracle Virtual Box and other products that use VCPU.
You could try a complete reinstall of Android Studio and make sure all updates are completed. There could be a bug in an older version of the emulator you are using that's fixed in a more recent release.
Edit
A couple more things you could try:
Open Android Virtual Device Manager, then click on options for virtual device, then wipe data, then cold boot.
Go to C:/users/(username)/AppData/Local/Android/Sdk/platform-tools in a terminal, then type adb kill-server, then adb start-server.
Edit
You could also try checking for memory leaks https://developer.android.com/studio/profile/memory-profiler and you could try increase the amount of RAM available for the emulator.
Go to Tools->Android->AVD Manager, then edit your AVD, then in the pop-up window click Show Advanced Settings, then finally increase the amount of RAM.
Edit
IT could be an issue with libGL or libstdc++. See here
It sounds like the emulator may have not installed correctly. Check these steps:
Ensure that you have installed Hyper-V . Documentation for running emulator on AMD
Then try this step to force a cold boot:
Android Studio Emulator and "Process finished with exit code -1073741511 (0xC0000139)"
If Its crashes again, then create a new emulator. You might also try and download a new image just to make sure that the one you installed is not corrupt.
You said you're using Windows 10? Error code 0xC0000409 is caused by a stack buffer overflow. It seems to have popped up a couple places all related by windows systems (might be totally irrespective of the android emulator). If this is the case I found a couple threads that might help solve your problem.
http://www.cplusplus.com/forum/windows/39061/
https://answers.microsoft.com/en-us/windows/forum/all/werfaultexe-the-exception-unknown-software/627da5c0-004a-e011-8dfc-68b599b31bf5?auth=1
http://windowsbulletin.com/solved-exception-code-0xc0000409-error/
https://www.tenforums.com/tutorials/16397-repair-install-windows-10-place-upgrade.html

I have got an AMD Ryzen CPU and Android emulator doesn't work

I have got an AMD Ryzen CPU and Android emulator doesn't work.
It doesn't start the emulator becouse the CPU doesn't support the x86 emulator
Update - My previous answer is no longer true. Google has added AMD and Hyper-V support into their latest beta. Thanks to ReverseCold for letting me know. Please see his answer below.
Update 2 - I had to set this up today. To save some googling, here is the powershell command to enable Hyper-V. Pulled from Microsoft's Docs
Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V -All
Make sure to run powershell as an administrator.
Update 3 - Turns out there's a difference between Windows Hypervisor Platform and Hyper-V. You'll need to enable the first one for Android emulation to work. Just click start and type Turn Windows features on or off until you see the control panel option of the same name. Then enable the feature from the menu that pops up after clicking that.
According to This answer, AMD virtualization for Android is only supported on Linux. If Ryzen becomes hugely popular, maybe they'll write one for Windows, but I won't be holding my breath.
The latest beta has support for Ryzen. Source
The following is from the google blog post: If you have an AMD processor in your computer you need the following setup requirements to be in place:
AMD Processor - Recommended: AMD® Ryzen™ processors
Android Studio 3.2 Beta or higher - download via Android Studio Preview page
Android Emulator v27.3.8+ - download via Android Studio SDK Manager
x86 Android Virtual Device (AVD) - Create AVD
Windows 10 with April 2018 Update
Enable via Windows Features: "Windows Hypervisor Platform"
Here is a list of ways to get around it:
genymotion personal is free but you need to register
Visual studio android emulator is also free and is fast. I had issues with it disconnecting on android studio
Physical device. You will have a hard time trying to see the sqlite database if it isn't rooted.
With the physical device you can download Vysor on play store and install the extension on google chrome. Then you can have the physical device on your monitor.
I managed to run the Android emulator on Windows 10 (AMD Ryzen 5 2600) after installing the KB4505903 update.
In my case, only two configuration requirements were needed:
Windows 10 May 2019 Update (1903), OS Build 18362.267
Enable via Windows Features: "Windows Hypervisor Platform" ("Платформа низкоуровневой оболочки Windows")
Gennymotion should work for amd users. I emailed them and they said yes it should work.
check here to see their specific requirements.
Yeah I have AMD CPU somehow it works now.
I don't have x86 installed by HAXM and it still works strange.
Gigabyte CPU/AMD Ryzen 7 ->
MIT Settings -> frequency settings -> advanced -> have SVM enabled
Go to windows turn on and off feature
-> if you're using windows home, not pro edition, then you need to find "windows Hypervision platform" then check mark it.
Create a new AVD virtual device, the newest version may or may not work. You have to do trial and error with different API versions like 25, 26, or newest one.
Somehow on SDK Tools, i don't have x86 intel HAXM installed, and it works fine? Does anyone know why it works without intel x86 on my AMD CPU? When i uninstalled it and did everything else again, it finally worked... Strange..
If you have an AMD processor in your computer you need the following setup requirements to be in place:
AMD Processor - Recommended: AMD® Ryzen™ processors
Android Studio 3.2 Beta or higher - download via Android Studio
Preview page
Android Emulator v27.3.8+ - download via Android Studio SDK Manager
x86 Android Virtual Device (AVD) - Create AVD
Windows 10 with April 2018 Update
Enable via Windows Features: "Windows Hypervisor Platform"
**Note:There is Hyper-V features... You should enable Windows Hypervisor Platform not Hyper-V. Windows Hypervisor Platform is at the bottom of features **
I know I am a bit late to answer this but after a few hours of research and verification, here is what I have found. As of July 2018, if you run AMD Ryzen CPU/APU, you should be able to run Android emulator. (see link). It does not work on my old AMD Phenom II X6 because the CPU needs to support SSSE3 and SSE4.1 features. I guess it's time for me to upgrade :) The toast message I received was "Emulator: emulator: WARNING: Host CPU is missing the following feature(s) required for x86_64 emulation: SSSE3 SSE4.1"
You can follow the instructions in the link above, although I also had to do these in my Android Studio.
In the Tools menu > Android SDK > SDK Tools (tab) > Uncheck the option "Intel x86 Emulator Eccelerator (HAXM installer)".
Go to Tools menu > AVD Manager > Ceate a new virtual device (choose an image for the x86-64 platform)
A related question was asked here - Ryzen 3 with VS android emulator - I've responded there and so thought to cross-link in case others missed it.
This might help you:
https://www.reddit.com/r/Amd/comments/cgpaq4/ryzen_android_emulator_whpx_fix_for_windows/
The issue seems to be to do with Windows and has been fixed in the insider builds - you can get it working by following the link above, and without having to become a Windows Insider.
--
Unfortunately After turning on Windows Hypervisor Platform I can not change the resolution window. It was fixed at non resolution recommended. I do not like at all. Here is my computer's information

Trouble running emulator in android studio

I am unable to run the emulator in android studio. I received a "Your cpu does not support required features (VT-x or SVM)" message. Someone told me to try and do what this link states "http://www.howtogeek.com/213795/how-to-enable-intel-vt-x-in-your-computers-bios-or-uefi-firmware/" which led me to a video and I tried following those directions but was unable to because first, there was no HyperV feature in the Windows features section. Second, there was no UEFI Firmware settings icon when I went to advanced settings in set up. How can I proceed from here to enable the VT-x in order for me to be able to use the emulator in Android studios? Thank you so much!!
Okay your cpu does not support is not the same as cannot use emulator you just have to use one that runs x86 images which is in fact GenyMotion...
https://www.genymotion.com/
sign up for free account and when you download you want the full install package with virtualbox included.
and it does support instantrun just like the google android emulators do
You will also find the android studio genymotion plugin at the same site to download and use with android studiio

Visual Studio 2015 RC Emulator for Android doesn't start

I have a problem with the Visual Studio 2015 RC Emulator for Android. The emulator is not starting when I'm starting debugging (F5) nor from "Tools > Visual Studio Emulator for Android...". The process is stuck on "Preparing virtual machine" and there is a "Xde.exe" process with 0% CPU usage in Task Manager. This happens for all virtual machines. Previous emulators (pre-RC) were working just fine.
The necessery APIs (19 and 21) are installed according to SDK manager.
I have tried re-installing Visual Studio and also repairing it but it didn't help.
How can I fix that?
Update:
Here are logs: http://pastebin.com/xgyTNkJ9 . The [Critical] The operation was canceled. lines are self explenatory. [Critical] Could not launch 'VS Emulator 5.5" KitKat (4.4) HDPI Phone' device.occured when I killed xde.exe in Task manager.
What's weird is a fact that when I import VHD file from %localappdata%\Microsoft\VisualStudioEmulator\Android\Containers\Local\Devices into Hyper-V manager it works just fine and I can even start it and use it. Unfortunately, I still can't debug application from Visual Studio that way.
Update 2:
So I've reinstalled the Windows on my notebook and same thing happens after installing Visual Studio 2015 RC. So two different hardware, one clean Windows installation and same effect.
This might be a duplicate of Visual studio (2015) emulator for android not working - XDE.exe - Exit Code 3.
I was having the same issue as yourself and this was solved by following the steps provided in this answer: https://stackoverflow.com/a/31698124/1010492.
The key for me was to disable the Network Sharing I had set on my Wi-fi adapter.
You are probably not a member of the Hyper-V Admins group on the computer. Do this:
Open Control Panel > Administrative Tools > Computer Management.
Expand "Local Users and Groups" and then click on "Groups."
Double click on "Hyper-V Administrators" group.
Click "Add" and add your username to the group.
If the group doesn't exist, you can create it using the PowerShell script in this blog post: http://blogs.msdn.com/b/virtual_pc_guy/archive/2010/09/28/creating-a-hyper-v-administrators-local-group-through-powershell.aspx
It may be that you do not have enough memory available to start the Hyper-V VM. If you go to Hyper-V Manager and attempt to start the emulator image, you'll be able to see if it starts at all or if you don't have enough free RAM on the machine.
I came up with a very genuine solution that can fulfill your basic need of running the emulator. All you need to do is follow these steps:
Sign in to https://www.genymotion.com/account/login/
Download Genymotion from there.
First Download and run the Emulator of your own choice from Genymotion.
[Start the Emulator From Start Button][2]
Then Keep it running and Open the Visual Studio.
Open your Solution,and while your Genymotion Emulator Running,You will see that at Play option,you will be having new Emulator device which will be Genymotion Device.
Deploy using that device.
Hurray!! Your Solution is Successful.

Android emulator shows nothing except black screen and adb devices shows "device offline"

I am just trying to start development in Android.
So, the problem is that when I try to launch an emulator by issuing the command emulator #A2, an emulator comes up on the screen. But even after waiting for as long as 2-3 hrs, all it shows is a black screen. Not even the Android home screen or the Android logo. Just a black screen. And while initially "adb devices" shows the emulator as offline.after 2-3 minutes the list of attached devices becomes blank.
I searched all over net and tried all the steps mentioned there like kill and restart adb, install java/android in a directory without spaces, but to no avail.
My Jdk and Android installations are in following folders:
C:\Java32BitInstallation
C:\AndroidSdkInstallation
Here's the list of stuff I have downloaded/installed for it:
Android SDK Tools, revision 13
Android SDK platforms tools, revision 10
SDK platform Android 4.0.3, API 15, revsion 1
Jdk jdk-7u3-windows-i586
In my path variable, I have added *C:\AndroidSdkInstallation\android-sdk\platform-tools;C:\AndroidSdkInstallation\android-sdk\tools;C:\Java32BitInstallation;C:\Java32BitInstallation\bin*
Also after reading somewhere from net I have added JAVA_HOME variable with its value as C:\Java32BitInstallation\ But still no use.
I have both IntelliJ and Eclipse installed on my system. But since for starting the emulator, I am not using any of these, I don't suspect any foul play with these.
I have been trying for past 10-12 days and have not been able to start the emulator, let alone write my first "Hello world" program.
Additional notes:
My system is a Windows 7 (64 bit) machine. Earlier I had installed 64 bit version of jdk, but the problem was present that time too. Now after searching on internet, I uninstalled that and installed 32 bit version of Java. But, again no use. One thing, though, this 32 bit version of Java (jdk 7 update 3), first install jre as part of jdk installation and then installs jre 7. So now I have 2 folders: jre and jre7 in the C:\Java32BitInstallation directory. Could this have to do anything with my emulator not turning up. Do I need to specify additional environment variables or modify the existing one?
BTW, did I mention the logcat shows nothing.
Update 25.07.2018:
The latest Android Studio version does not have this option anymore.
If the problem persists try to switch between the values of the "Emulated Performance" dropdown in the Verify Configuration dialogue (if available) or refer to the Configure Emulator graphics rendering and hardware acceleration.
Update 26.02.2014:
There are two hints in the Configuring Graphics Acceleration chapter from developer.android.com.
Caution: As of SDK Tools Revision 17, the graphics acceleration feature for the emulator is experimental; be alert for incompatibilities and errors when using this feature.
and
Start the AVD Manager and create a new AVD with the Target value of Android 4.0.3 (API Level 15), revision 3 or higher.
So Android 4.0.3 (API Level 15) seems to be the minimum requirement for graphics acceleration.
Original answer
I have had the same issue with the latest Android SDK.
I simply deactivated the checkbox "Use Host GPU" within the settings of the virtual device and it started working again.
The "Use Host GPU" does only work for me with Android 4.2 as "Target".
I have recently the same issue in emulator, Nexus 5 (Android O). I have go to Android Virtual Device Manager and Wipe User Data and it solved my Problem.
I had issues with getting the larger devices to emulate (Nexus7 and 10), while the phone sized emulators worked great. Would just keep getting a black screen with nothing for hours with the tablets. What helped was actually the OPPOSITE of what most people here are recommending: after setting the tick box for 'Use Host GPU' and setting the target to the highest android (4.4.2 at the time of this writing) the 7 and 10 work as expected!
Have you tried the power button :) ... it really worked for me. Actually emulator saves the device state before closing so at the last run if you switched off the device & closed the emulator then in the next run it will load previous state & display switched off phone aka blank screen. Although there might be many other causes of this issue.
Checking "Wipe user data" in the Launch Options fixed it for me.
Go to Android Virtual Device Manager->Select your device->Start->Check "Wipe user data"->Launch
Mac Users: Unfortunately, if you have an older Mac (late 2009 for example) and are using Yosemite, you cannot use HAXM for 64 bit architecture. According to the release notes on HAXM:
HAXM driver does not support emulating a 64 bit system image on Intel systems based on Core microarchitecture (Core, Core2 Duo etc.). All systems based on Nehalem and beyond are supported. (Corei3, Core i5 and Core i7 machines).
I spent a day trying to figure this problem out when I came upon this quote. The only thing that works is to use the non-x86 version of the latest OS (e.g. Lollipop Android 5.0.1 armeabi-v7a) in your AVD
How i solved the issue.. Open AVD manager, CLick on the drop-down arrow:
select >> wipe data after that u can select >> cold boot now..
It worked for me
Here is how i got it solved :
I ran the emulator with following command :
sudo /home/code/Android/Sdk/tools/emulator -avd Nexus_S_API_21 -netspeed full -netdelay none -debug-init -logcat '*:v'
and received the following in the output :
NAND: could not write file /tmp/android-code/TMP7.tmp, No space left on device. (similar error, could not reproduce it)
So, i just freed up some disk space from my /home directory in ubuntu (for windows free the C: drive space) and it then booted smoothly.
Do factory reset in "Android Device Manager".
In newer versions of Android Studio, this is called "Wipe Data", and it is in the right-click menu for the device in the virtual device manager.
Also had this issue out of the blue. Android studio was taking up 100% of CPU and in expo I had the following error:
Couldn't start project on Android: Error running adb: This computer is not authorized to debug the device. Please follow the instructions here to enable USB debugging: https://developer.android.com/studio/run/device.html#developer-device-options. If you are using Genymotion go to Settings -> ADB, select "Use custom Android SDK tools", and point it at your Android SDK directory.
Cold boot fixed it for me, like boltup_im_coding's answer. You can also cold boot this way if it's already running (with the black screen).
Make sure that you've installed the latest HAXM revision. I had the same blank screen problem with version 1.0.1 while 1.0.8 was already available. The installer can be downloaded via the SDK tools, to actually install the module you would have to execute
android-sdk-directory\extras\intel\Hardware_Accelerated_Execution_Manager\intelhaxm.exe
I changed it to always "cold boot" to fix my problem. Prior to this, when I ran adb devices it always showed as offline.
Had this issue on my Nexus 7,Nexus 10 & Pixel as well that means in all the emulators.
After days of struggling with this issue,
I figured it out finally.
Well, there are a lot of answers above which may work or may not for you because their configuration may vary slightly than yours.
I'll tell you my solution:
When creating those emulators, I checked Hardware - GLES 2.0 in Graphics for better performance.
And for me it was the issue.
If you've done the same then,
Go to AVD Manager -> Select your emulator -> Click on Edit configuration (in Actions column marked as pencil) -> in Emulated performance - Graphics -> Select Software - GLES 2.0.
Then click on Show Advanced Settings -> Set none for both Front and Back camera and hit Finish.
Now select your emulator in AVD Manager and click on Dropdown arrow in Actions column -> select Cold Boot Now.
And yay you're ready to go 😀
Helped for me (windows 10, intel):
Disable Hyper-V in windows
Uninstall HAXM ( "Intel Hardware Accelrated ..." in control panel)
reboot
Install HAXM using android studio (Settings -> Android SDK -> SDK Tools -> Intel x86 Emulator Accelerator (HAXM Installer) -> install)
Run emulator (Also you may try Wipe VD data/Cold boot VD)
By the sound of it you have a misconfigured device. If you do it will never start and never show anything in Logcat.
I'd recommend creating a new device using one of the default "Device Definitions" available in the AVD Manager. It's as easy as highlighting the device type you want in the "Device Definitions" tab and clicking the "Create AVD..." button, then filling out a few details. I'd start by adjusting "Internal Storage" to around 8GB and (maybe) an "SD Card" of 2GB while leaving everything else the same. Try starting the device and if you see "Android" pop up onscreen you're running. The first boot usually takes awhile so just hang on and watch Logcat for any issues (the "DDMS" perspective helps here).
If you still see a black screen with a default device definition you've got problems elsewhere that are causing the device to fail. Digging through logs may be your only chance if that's the case. You can always try re-downloading the ADT and re-installing the SDKs if nothing else works.
The goal here is to get you up and running with a (very) basic device, so don't shoot for uber impressive specs at this point, just shoot for trying to make it run. Once that happens try adjusting the settings one-by-one until you have it spec'd out the way you like. Just keep in mind that the emulator has its limitations and its no substitute for a real device (Although it works most of the time ;)
This is a known bug if you selected "Use host GPU" option while creating AVD.
https://code.google.com/p/android/issues/detail?id=28614
Uncheck the option and it should work!
Just try to set CPU/ABI on "Intel Atom (x86)" and deactivate the checkbox "Use Host GPU".
The Problems associated with the Black window of the emulator:
Happens when a new windows is installed. Problem associated with graphics of the windows is on the CD of windows .You have to Update windows and follow the following steps.
If Emulated Performance Graphics is (Software GLES then select it to-->Automatic)
Or
If Emulated Performance Graphics is (Automatic then select it to-->Software GLES)
this alternation can solve this problem.
I was having this issue on my Mac. When you create the device if you change "Graphics" from "Automatic" to "Software" it fixes the issue, or it least it did for me.
The following fix worked for me:
Locate the AVD folder in ~/.android/avd
Open config.ini
Replace the following settings with these values:
hw.gpu.enabled=yes
hw.gpu.mode=on
Save and close the file
Do not open the AVD settings screen within Android Studio or it will revert the above settings
Start the emulator
Thanks to Sunsugh Park for providing the fix.
I have reported this to Google at Black screen starting API 15. Please star the issue to get them to fix it.
Edit
Actually, while the emulator booted ok, it crashed after opening an app. So the emulator team must have disabled hardware graphics for a reason. Unfortunately, it appears to be impossible to get the emulator to work.
I had the same problem on API 28, and the fix turned out to be as below;
Enabling Skia rendering for Android UI
When using images for API 27 or later, the emulator can render the Android UI with Skia, which can render more smoothly and efficiently.
To enable Skia rendering, use the following commands in adb shell:
su
setprop debug.hwui.renderer skiagl
stop
start
https://developer.android.com/studio/run/emulator-acceleration#accel-graphics
I too got the same problem. When i changed the Eclipse from EE to Eclipse Classic it worked fine. in Win professional 64Bit.
Have a try it may work for you too..
For a workaround try Android 4.0.3 (API 15) with the Intel Atom (x86) image. I could capture DDMS screenshots with both "use host gpu" and HAXM enabled. Only this combination worked for me.
I also had the same problem. I figured out that the HAXM hardware accelerator was recently updated but not reinstalled since the update manager just updates the installer package which get saved to your hard drive. You will need to remove HAXM and then run that installer package to complete the update. Usualy this gets installed into ANDROID-SDK-ROOT\android-sdk\extras\intel\Hardware_Accelerated_Execution_Manager. Where ANDROID-SDK-ROOT is the location where your android sdk is located.
For me, I had to turned off both front and back camera. Hope this helps!
I use Microsoft's lightning fast Android Emulators utilizing Hyper-V, and I had the same black screen for every Android emulator that I created no matter how I set the GPU Mode (auto, host, mesa, angle, swiftshader, off). Though my situation is apparently different form that of the OP, I thought it might be useful for those using Microsoft Android emulators and coming here after searching "android emulator black screen".
The solution in my case is updating all the Android tools:
Visual Studio > Tools > Android > Android SDK Manager > Tools
As of today (2019-02-01), Android emulators would have this black screen problem if you have a fresh install of Visual Studio 2017. VS shows notifications automatically for updates of NuGet packages, extension tools, etc., but NOT for Android tool updates. You have to check and update them manually.
I've managed to launch and debug an Android testing application on the Android emulator through Delphi.
I have Windows 7 64 bit, 4GB RAM, a dual core processor at 3GHz and Delphi XE 5.
Below is a link that I've prepared in a hurry for my colleagues at work but I will make it better by the first chance:
Debug Android Apps with Delphi
Forgive my English language but I am not a native English speaker. I hope you will find this small tutorial
I was having this problem after I got the blue screen of death while running my emulator. Here's my solution (for Windows at least). My solution is too completely re-install the AVD. The problem with the normal un-installation process for Android Studio is that it doesn't remove everything, so if your AVD files are corrupted, they will remain corrupted on re-install.
In order to fix this, I deleted two directories:
C:\Users\(My Username)\.Android
and
C:\Users\(My Username)\.AndroidStudio3.1
Then I re-ran in the installer.
I think this is the most foolproof solution if your emulator was previously working because it forces a complete refresh of the AVD component of Android Studio.
Another source of error could be the length of the PATH system variable (on Windows systems). Running intel based images with a PATH variable longer than 2047 characters, seems to pass an empty value of this variable to the console / emulator, so it cannot start correctly.
Here is an article describing this behaviour:
https://software.intel.com/en-us/articles/limitation-to-the-length-of-the-system-path-variable
I had the same problem. Reducing the total length of this system variable to 1354 chars by removing unused / non-existent paths fixed it for me.
I had the same problem. Here's my solution (for Mac OS). I just downgrade the version of the Android Emulator (from 28.0.3 to 27.3.8). Here is a detailed instruction how to do it.