这个问题通常出现在应用程序处于后台状态下。如果尝试从后台启动多个Activity，则会发生错误。要解决这个问题，可以使用以下代码来重写应用程序的后台流程：

public class MyApplication extends Application {

    private static MyApplication instance;

    public static synchronized MyApplication getInstance() {
        return instance;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        instance = this;

        registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
            @Override
            public void onActivityCreated(Activity activity, Bundle savedInstanceState) { }

            @Override
            public void onActivityStarted(Activity activity) { }

            @Override
            public void onActivityResumed(Activity activity) { }

            @Override
            public void onActivityPaused(Activity activity) { }

            @Override
            public void onActivityStopped(Activity activity) { }

            @Override
            public void onActivitySaveInstanceState(Activity activity, Bundle outState) { }

            @Override
            public void onActivityDestroyed(Activity activity) {
                // 当Activity被销毁时，从Activity列表中删除该Activity
                MyActivityManager.getInstance().remove(activity);
            }
        });
    }
}

public class MyActivityManager {

    private static MyActivityManager instance;
    private final List activities = new LinkedList<>();

    public static synchronized MyActivityManager getInstance() {
        if (instance == null) {
            instance = new MyActivityManager();
        }
        return instance;
    }

    private MyActivityManager() { }

    /**
     * 添加Activity到列表中
     * @param activity
     */
    public synchronized void add(Activity activity) {
        activities.add(activity);
    }

    /**
     * 从列表中删除Activity
     * @param activity
     */
    public synchronized void remove(Activity activity) {
        activities.remove(activity);
    }

    /**
     * 获取列表中的最后一个Activity
     * @return
     */
    public synchronized Activity getLast() {
        if (activities.size() > 0) {
            return activities.get(activities.size() - 1);
        }
        return null;
    }

    /**
     * 移除所有的Activity