System.InvalidOperationException: Specified elemen

Question

I have a WPF application running without any issues in my windows 8 OS development machine. But when i try to run the same in Windows 7 machine i am getting the error

System.InvalidOperationException: Specified element is already the logical child of another element. Disconnect it first.

The detailed error log is

        [CDATA[Set property 'System.Windows.FrameworkElement.Style' threw an exception.
            LoadBaml at offset 481 in file:line:column <filename unknown>:0:0

            System.InvalidOperationException: Specified element is already the logical child of another element. Disconnect it first.
               at System.Windows.FrameworkElement.ChangeLogicalParent(DependencyObject newParent)
               at System.Windows.FrameworkElement.AddLogicalChild(Object child)
               at System.Windows.Controls.ContentControl.OnContentChanged(Object oldContent, Object newContent)
               at System.Windows.Controls.ContentControl.OnContentChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
               at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
               at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
               at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
               at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
               at System.Windows.StyleHelper.ApplyStyleOrTemplateValue(FrameworkObject fo, DependencyProperty dp)
               at System.Windows.StyleHelper.InvalidateContainerDependents(DependencyObject container, FrugalStructList`1& exclusionContainerDependents, FrugalStructList`1& oldContainerDependents, FrugalStructList`1& newContainerDependents)
               at System.Windows.StyleHelper.DoStyleInvalidations(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle)
               at System.Windows.StyleHelper.UpdateStyleCache(FrameworkElement fe, FrameworkContentElement fce, Style oldStyle, Style newStyle, Style& styleCache)
               at System.Windows.FrameworkElement.OnStyleChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
               at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
               at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
               at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
               at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
               at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
               at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
               at System.Windows.Baml2006.WpfKnownMemberInvoker.SetValue(Object instance, Object value)
               at MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(XamlMember member, Object obj, Object value)
               at MS.Internal.Xaml.Runtime.ClrObjectRuntime.SetValue(Object inst, XamlMember property, Object value)]]

I have no idea which element XAML or code behind causing this issue. Any help to find out reason for this strange issue?

Finally able to find the reason for error I have a ToggleButton style in the application which is defined in App.xaml like this

  <Style x:Key="ONStateLabelLib" TargetType="Label">
        <Setter Property="Background" Value="#A1A1A1"></Setter>
        <Setter Property="Foreground" Value="Black"></Setter>

        <Setter Property="Margin" Value="0"></Setter>
        <Setter Property="Padding" Value="0"></Setter>

        <Setter Property="Cursor" Value="Hand"/>
        <Setter Property="Width" Value="45"></Setter>


        <Setter Property="VerticalContentAlignment" Value="Center"></Setter>
        <Setter Property="HorizontalContentAlignment" Value="Center"></Setter>

        <Setter Property="FontSize" Value="14"/>
        <Setter Property="FontFamily" Value="Arial"/>
    </Style>
    <Style x:Key="OFFStateLabelLib" TargetType="Label">

        <Setter Property="Cursor" Value="Hand"/>
        <Setter Property="Margin" Value="0"></Setter>
        <Setter Property="Padding" Value="0"></Setter>

        <Setter Property="FontSize" Value="14"/>
        <Setter Property="FontFamily" Value="Arial"/>
        <Setter Property="FontWeight" Value="ExtraLight"/>

        <Setter Property="Foreground" Value="#515151"></Setter>
        <Setter Property="Background" Value="#393939"></Setter>


        <Setter Property="Width" Value="45"></Setter>

        <Setter Property="BorderBrush" Value="#A1A1A1"></Setter>
        <Setter Property="BorderThickness" Value="2"></Setter>


        <Setter Property="VerticalContentAlignment" Value="Center"></Setter>
        <Setter Property="HorizontalContentAlignment" Value="Center"></Setter>
    </Style>

    <Style x:Key="OnOffToggleStyleLib" TargetType="ToggleButton" >
        <Setter Property="VerticalAlignment" Value="Center"></Setter>
        <Setter Property="Width" Value="90"></Setter>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ToggleButton">
                    <ContentPresenter  VerticalAlignment="Center" />
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter Property="Background" Value="Transparent">
                            </Setter>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Style.Triggers>
            <Trigger Property="IsChecked" Value="True">
                <Setter Property="Content">
                    <Setter.Value>
                        <DockPanel Margin="0">
                            <Label DockPanel.Dock="Left" Style="{StaticResource ResourceKey=ONStateLabelLib}" >YES</Label>
                            <Label Style="{StaticResource ResourceKey=OFFStateLabelLib}" >NO</Label>
                        </DockPanel>
                    </Setter.Value>
                </Setter>
            </Trigger>
            <Trigger Property="IsChecked" Value="False">
                <Setter Property="Content">
                    <Setter.Value>
                        <DockPanel Margin="0">
                            <Label DockPanel.Dock="Left" Style="{StaticResource ResourceKey=OFFStateLabelLib}">YES</Label>
                            <Label Style="{StaticResource ResourceKey=ONStateLabelLib}" >NO</Label>
                        </DockPanel>
                    </Setter.Value>
                </Setter>
            </Trigger>
        </Style.Triggers>
    </Style>

And i use the Toggle Button in 2 pages Page1.xaml and Page2.xaml like this

  <ToggleButton Margin="5" Grid.Row="0" 
     ToolTip="{Binding Path=localResource.reader_tooltip_settings_fullscreen,Source={StaticResource      DbookLanguageManagerDynamic}}"  Grid.Column="1"
     Name="btn_fullScreen" Click="btn_fullScreen_Clicked"
      Style="{StaticResource ResourceKey=OnOffToggleStyleLib}" />   

Application Loads Page1.xaml first and While Navigating to Page2.xaml i ma getting above exception .

Now can some one help to solve this?

Answer 1

Try changing the Content property setter to ContentTemplate, and using a DataTemplate as value:

<Style
    x:Key="OnOffToggleStyleLib"
    TargetType="ToggleButton">
    <Setter
        Property="VerticalAlignment"
        Value="Center"></Setter>
    <Setter
        Property="Width"
        Value="90"></Setter>
    <Setter
        Property="Template">
        <Setter.Value>
            <ControlTemplate
                TargetType="ToggleButton">
                <ContentPresenter
                    VerticalAlignment="Center" />
                <ControlTemplate.Triggers>
                    <Trigger
                        Property="IsMouseOver"
                        Value="True">
                        <Setter
                            Property="Background"
                            Value="Transparent">
                        </Setter>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Style.Triggers>
        <Trigger
            Property="IsChecked"
            Value="True">
            <Setter
                Property="ContentTemplate">
                <Setter.Value>
                    <DataTemplate>
                        <StackPanel
                            Orientation="Horizontal">
                            <Label
                                DockPanel.Dock="Left"
                                Style="{StaticResource ResourceKey=ONStateLabelLib}">YES</Label>
                            <Label
                                Style="{StaticResource ResourceKey=OFFStateLabelLib}">NO</Label>
                        </StackPanel>
                    </DataTemplate>
                </Setter.Value>
            </Setter>
        </Trigger>
        <Trigger
            Property="IsChecked"
            Value="False">
            <Setter
                Property="ContentTemplate">
                <Setter.Value>
                    <DataTemplate>
                        <StackPanel
                            Orientation="Horizontal">
                            <Label
                                DockPanel.Dock="Left"
                                Style="{StaticResource ResourceKey=OFFStateLabelLib}">YES</Label>
                            <Label
                                Style="{StaticResource ResourceKey=ONStateLabelLib}">NO</Label>
                        </StackPanel>
                    </DataTemplate>
                </Setter.Value>
            </Setter>
        </Trigger>
    </Style.Triggers>
</Style>

I also swapped the DockPanel with a StackPanel, it's a better approach in my opinion. Let me know if it works :)