NavigationService.cs

public class ViewNavigationService : INavigationService
{
    private readonly object _sync = new object();
    private readonly Dictionary<string, Type> _pagesByKey = new Dictionary<string, Type>();
    private readonly Stack<NavigationPage> _navigationPageStack =
        new Stack<NavigationPage>();
    private NavigationPage CurrentNavigationPage => _navigationPageStack.Peek();

    public void Configure(string pageKey, Type pageType)
    {
        lock (_sync)
        {
            if (_pagesByKey.ContainsKey(pageKey))
            {
                _pagesByKey[pageKey] = pageType;
            }
            else
            {
                _pagesByKey.Add(pageKey, pageType);
            }
        }
    }

    public Page SetRootPage(string rootPageKey)
    {
        var rootPage = GetPage(rootPageKey);
        _navigationPageStack.Clear();
        var mainPage = new NavigationPage(rootPage);
        _navigationPageStack.Push(mainPage);
        return mainPage;
    }

    public string CurrentPageKey
    {
        get
        {
            lock (_sync)
            {
                if (CurrentNavigationPage?.CurrentPage == null)
                {
                    return null;
                }

                var pageType = CurrentNavigationPage.CurrentPage.GetType();

                return _pagesByKey.ContainsValue(pageType)
                    ? _pagesByKey.First(p => p.Value == pageType).Key
                    : null;
            }
        }
    }

    public async Task GoBack()
    {
        var navigationStack = CurrentNavigationPage.Navigation;
        if (navigationStack.NavigationStack.Count > 1)
        {
            await CurrentNavigationPage.PopAsync();
            return;
        }

        if (_navigationPageStack.Count > 1)
        {
            _navigationPageStack.Pop();
            await CurrentNavigationPage.Navigation.PopModalAsync();
            return;
        }

        await CurrentNavigationPage.PopAsync();
    }

    public async Task NavigateModalAsync(string pageKey, bool animated = true)
    {
        await NavigateModalAsync(pageKey, null, animated);
    }

    public async Task NavigateModalAsync(string pageKey, object parameter, bool animated = true)
    {
        var page = GetPage(pageKey, parameter);
        NavigationPage.SetHasNavigationBar(page, false);
        var modalNavigationPage = new NavigationPage(page);
        await CurrentNavigationPage.Navigation.PushModalAsync(modalNavigationPage, animated);
        _navigationPageStack.Push(modalNavigationPage);
    }

    public async Task NavigateAsync(string pageKey, bool animated = true)
    {
        await NavigateAsync(pageKey, null, animated);
    }

    public async Task NavigateAsync(string pageKey, object parameter, bool animated = true)
    {
        var page = GetPage(pageKey, parameter);
        await CurrentNavigationPage.Navigation.PushAsync(page, animated);
    }

    private Page GetPage(string pageKey, object parameter = null)
    {

        lock (_sync)
        {
            if (!_pagesByKey.ContainsKey(pageKey))
            {
                throw new ArgumentException(
                    $"No such page: {pageKey}. Did you forget to call NavigationService.Configure?");
            }

            var type = _pagesByKey[pageKey];
            ConstructorInfo constructor;
            object[] parameters;

            if (parameter == null)
            {
                constructor = type.GetTypeInfo()
                    .DeclaredConstructors
                    .FirstOrDefault(c => !c.GetParameters().Any());

                parameters = new object[]
                {
                };
            }
            else
            {
                constructor = type.GetTypeInfo()
                    .DeclaredConstructors
                    .FirstOrDefault(
                        c =>
                        {
                            var p = c.GetParameters();
                            return p.Length == 1
                                   && p[0].ParameterType == parameter.GetType();
                        });

                parameters = new[]
                {
                    parameter
                };
            }

            if (constructor == null)
            {
                throw new InvalidOperationException(
                    "No suitable constructor found for page " + pageKey);
            }

            var page = constructor.Invoke(parameters) as Page;
            return page;
        }
    }
}

I got this exception "No suitable constructor found for page "
in this part

if (parameter == null)
                {
                    constructor = type.GetTypeInfo()
                        .DeclaredConstructors
                        .FirstOrDefault(c => !c.GetParameters().Any());

                    parameters = new object[]
                    {
                    };
                }

even page has empty constructor