dotnet/maui · error · Exception

The emulator did not finish booting in time.

Error message

The emulator did not finish booting in time.

What it means

Thrown when the emulator boot-watchdog loop exceeds EmulatorBootTimeoutSeconds (10 minutes) without sys.boot_completed reporting '1'. Each second the loop checks SafeAdbShell('getprop sys.boot_completed'); if the counter passes the budget it aborts. At 90s in CI it also tries restarting the ADB server to recover from auth issues.

Source

Thrown at eng/devices/android.cake:769

	{
		settings.Serial = DEVICE_UDID;
	}

	if (waitForBoot)
	{
		Information("Waiting for the emulator to finish booting...");

        // Wait for the emulator to finish booting
        var waited = 0;
        var total = EmulatorBootTimeoutSeconds;
        while (SafeAdbShell("getprop sys.boot_completed", settings).FirstOrDefault() != "1")
		{
		    System.Threading.Thread.Sleep(1000);

            Information("Waiting {0}/{1} seconds for the emulator to boot up.", waited, total);
            if (waited++ > total)
            {
                throw new Exception("The emulator did not finish booting in time.");
            }

            // At 90 seconds, restart ADB server to recover from authorization issues
            if (waited == 90 && IsCIBuild())
            {
                Information("Emulator boot taking longer than expected (90/{0} seconds). Restarting ADB server...", total);
                try
                {
                    Information("Stopping ADB server...");
                    AdbKillServer(settings);
                    System.Threading.Thread.Sleep(2000);
                    
                    Information("Starting ADB server...");
                    AdbStartServer(settings);
                    System.Threading.Thread.Sleep(2000);
                    
                    Information("ADB server restart completed. Continuing to wait for emulator boot...");
                }

View on GitHub (pinned to f377ff1c5e)

Solutions

1. Ensure hardware acceleration is enabled (Hypervisor Framework on macOS, KVM on Linux, Hyper-V/WHPX on Windows) — without it boot can exceed 10 min.
2. Wipe the AVD data/cold-boot: delete the snapshot or recreate the AVD to clear corruption.
3. Increase EmulatorBootTimeoutSeconds for slow agents, or allocate more RAM/CPU to the emulator.
4. Watch the 90-second ADB-restart log line; if it appears, the issue is likely ADB authorization — ensure ADB keys are set up (see ADB key errors).
5. Check emulator logs (e.g. ~/.android/avd/<name>.avd/logs) for the underlying hang.

// Pre-flight: confirm emulator is reachable before boot-watchdog
if (!SafeAdbShell("getprop sys.boot_completed", settings).Any()) {
    Warning("Emulator not responding to adb; boot watchdog may time out.");
}

for (int bootAttempt = 1; bootAttempt <= 2; bootAttempt++) {
    try {
        WaitForEmulatorBoot(settings, EmulatorBootTimeoutSeconds);
        break;
    } catch when (bootAttempt < 2) {
        Warning("Boot timed out; wiping AVD data and retrying.");
        WipeAndRestartEmulator(settings);
    }
}

When it happens

Trigger: The emulator fails to reach sys.boot_completed=1 within 600 seconds. Causes include slow/emulator-starved hosts, AVD stuck on boot animation, disk image corruption, HAXM/Hyper-V/KVM acceleration unavailable, or ADB authorization blocking the device.

Common situations: Underpowered CI agents without hardware acceleration; a corrupted AVD snapshot; cold boot of a large API-level image; ADB key authorization pending; emulator process hung.

Related errors

• All key generation methods failed. Unable to create ADB keys
• ADB keys were not created successfully.
• Failed to push ADB keys after multiple attempts.
• Environment variable 'ANDROID_SDK_ROOT' or 'ANDROID_HOME' mu
• JAVA_HOME environment variable isn't set. Set it to your JDK

AI-assisted analysis of dotnet/maui@f377ff1c5e (2026-08-13). Data as JSON: /api/errors/fcd8bb012fb45ab8. Report an issue: GitHub.