Why do i get this error

Question

When i start debugging and i press a NavigationMenuItem, i get this error (See Screenshot).

the NavigationPages are in the folder NavigationMenu.
Does anyone know how to fix this

My code is

MainPage.xaml

<UserControl

x:Class="Phone_Connection.MainPage"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:local="using:Phone_Connection"

xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

mc:Ignorable="d">

<Grid>

    <NavigationView x:Name="NavView"

                    IsBackButtonVisible="Collapsed"

                    IsPaneOpen="True"

                    SelectionChanged="NavigationView_SelectionChanged">

        <NavigationView.MenuItems>

            <NavigationViewItem Icon="Home" Content="Home" Tag="Home"/>

            <NavigationViewItem Icon="CellPhone" Content="Phone" Tag="Phone"/>

            <NavigationViewItem Icon="Audio" Content="Audio" Tag="Audio"/>

            <NavigationViewItem Content="AirPlay" Tag="AirPlay">

                <NavigationViewItem.Icon>

                    <FontIcon Glyph="&#xE95A;" />

                </NavigationViewItem.Icon>

            </NavigationViewItem>

        </NavigationView.MenuItems>

        <Frame x:Name="contentFrame"/>

    </NavigationView>

</Grid>
```</UserControl>  
  
MainPage.xaml.cs  
  
using Microsoft.UI.Xaml;

using Microsoft.UI.Xaml.Controls;

using Phone_Connection.NavigationMenu;

namespace Phone_Connection

{

public sealed partial class MainPage : UserControl

{

public MainPage()

{

    this.InitializeComponent();

    contentFrame = new Frame();

}

private void NavigationView_SelectionChanged(NavigationView sender, NavigationViewSelectionChangedEventArgs args)

{

    if (args.SelectedItem is NavigationViewItem selectedItem)

    {

        var tag = selectedItem.Tag.ToString();

        NavigateTo(tag);

    }

}

private void NavigateTo(string pageName)

{

    // Zorg ervoor dat contentFrame niet null is

    if (contentFrame == null)

    {

        // Mogelijk een foutmelding of logica om te controleren waarom contentFrame null is

        return;

    }

    // Load the content based on the pageName

    switch (pageName)

    {

        case "Home":

            contentFrame.Navigate(typeof(NavigationMenu.HomePage)); // Zorg ervoor dat HomePage bestaat

            break;

        case "Phone":

            contentFrame.Navigate(typeof(NavigationMenu.PhonePage)); // Zorg ervoor dat PhonePage bestaat

            break;

        case "Audio":

            contentFrame.Navigate(typeof(NavigationMenu.AudioPage)); // Zorg ervoor dat AudioPage bestaat

            break;

        case "AirPlay":

            contentFrame.Navigate(typeof(NavigationMenu.AirPlayPage)); // Zorg ervoor dat AirPlayPage bestaat

            break;

    }

}

}

Answer 1

In that exception dialog, click the stack trace and look at it carefully. The base code you showed appears fine but the Navigate method may be throwing an exception. The stack trace will help clarify this.

Answer 2

Hi @Wannes Aneca ,

Welcome to Microsoft Q&A!

I can't reproduce this error using your code, but the homepage is not displayed.

According to the official sample, there is no need to initialize the Frame again on the code side. It is recommended to delete contentFrame = new Frame();.

Thank you.

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