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.

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

• ADB keys were not created successfully.
• All key generation methods failed. Unable to create ADB…
• Failed to push ADB keys after multiple attempts.
• Active Shell Item not set. Have you added any Shell Items…
• Activity OnCreate was not called prior to loading the…

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

Appendix: 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)