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ANDROID EMULATOR

Giorgio Sfiligoi 616 Reputation points
2026-03-05T09:33:34.81+00:00

Consider the following simple code snippet:

    [RelayCommand]
    public async Task Test()
    {
        for (int i = 0; i < 200; i++)
        {
            Debug.WriteLine($"i = {i.ToString()}");
        }
    }

It runs as expected in Windows Machine and on a cellular phone. However, the Android Emulator (API 36) often stops before the end of the count, and when this happens, it also closes Visual Studio.

I tried to remove and re-install the Emulator, but did not solve this problem.

Developer technologies | .NET | .NET MAUI
Answer accepted by question author
  1. Nancy Vo (WICLOUD CORPORATION) 880 Reputation points Microsoft External Staff Moderator
    2026-03-06T08:04:24.8866667+00:00

    Hi @Giorgio Sfiligoi ,

    Thanks for reaching out.

    From the code and error you provided, the problem is caused by the fast loop flooding the debug output window.

    Rapid Debug.WriteLine calls overwhelm the debugger connection on the Android emulator (especially API 36), causing it to freeze or crash Visual Studio. This doesn't happen on Windows or real phones because their debug channels handle it better.

    I recommend some sulutions below:

    First, try to add a small delay inside the loop:

    
[RelayCommand]

public async Task Test()

{

    for (int i = 0; i < 200; i++)

    {

        Debug.WriteLine($"i = {i}");

        await Task.Delay(5);  // or 10 – just enough to slow output

    }

}

    Then rebuild and run.

    Extra tips if still issues:

    • Update Visual Studio to latest.
    • Try a lower API emulator (e.g. API 34 or 33) – newer APIs can be unstable for heavy debug output.
    • Check Output window for clues before crash.

    This is a known emulator/debugger limitation, not your code bug.

    Hope this helps. If you found my response helpful or informative, I would greatly appreciate it if you could follow this guidance provide feedback. Thank you.

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  1. Q&A Assist
    2026-03-05T09:33:47.9433333+00:00
    AI generated content. This question contains an answer created with AI from Q&A Assist. Learn more

    The behavior indicates an emulator/Android tooling instability rather than a problem with the loop or command itself, especially since it works on Windows and a physical phone.

    Use the following checks and troubleshooting steps focused on the Android emulator and ADB on Windows:

    1. Verify the emulator is correctly visible to the Android SDK
      1. Start the Android emulator from Android Device Manager (start the AVD you’re using).
      2. Open a command prompt and navigate to the adb location (adjust if SDK path differs): 
              cd "C:\Program Files (x86)\Android\android-sdk\platform-tools"
      adb devices
      3. Confirm the emulator appears as a device (for example emulator-5554 device).
      4. If it does not appear, open the Android SDK Manager, apply all updates, and try again.
    2. Restart ADB and emulator
      • From Visual Studio, restart ADB (Tools → Android → Restart ADB Server if available in the environment).
      • Close all running emulators.
      • Start the emulator again from Android Device Manager, then deploy the app.
    3. Start the emulator from the command line with verbose output
      • Locate the AVD folder under %userprofile%\.android\avd.
      • Start the emulator manually to see detailed logs: 
             "C:\Program Files (x86)\Android\android-sdk\emulator\emulator.exe" -partition-size 2000 -no-boot-anim -verbose -feature WindowsHypervisorPlatform -avd <your_avd_name> -prop monodroid.avdname=<your_avd_name>
      • Reproduce the issue and watch for errors in the console output that might indicate crashes or MMIO access errors.
    4. Check for MMIO access error
      • If the emulator shows “An MMIO access error has occurred”, simply restarting the emulator is the recommended fix.
    5. Review Device Manager logs
      • Check logs under %userprofile%\AppData\Local\Xamarin\Logs\16.0 (or similar version folder) for DeviceManager.log entries around the time of the crash.
      • These logs can reveal emulator startup or communication issues that might be causing Visual Studio to close.
    6. Update and reconfigure the AVD
      • Ensure the AVD uses an image appropriate for the machine’s CPU and that hardware acceleration is enabled as recommended for performance and stability.
      • If the current AVD is unstable, create a new AVD (for example, a Pixel device with a supported API level) and test the same code there.

    If the loop runs correctly on a physical device and on Windows, and only the emulator causes Visual Studio to close, focus on stabilizing or replacing that emulator instance (new AVD, updated SDK/emulator, or testing on a different API level) rather than changing the app code.

    References:

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