scrollviewer the property 'content' is set more than once

Question

Here my code:

<Grid Style="{StaticResource LayoutRootStyle}">
    <Grid.RowDefinitions>
        <RowDefinition Height="140"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <ScrollViewer 
            Grid.RowSpan="2" Style="{StaticResource HorizontalScrollViewerStyle}"
            HorizontalScrollBarVisibility="Visible" >
            <!-- The elements you want to be horizontally scrollable goes here -->
            <!-- Horizontal scrolling grid used in most view states -->

        <GridView
            Name="itemGridView"
            AutomationProperties.AutomationId="ItemsGridView"
            AutomationProperties.Name="Items"
            TabIndex="1"
            Padding="100,136,116,46"
            ItemsSource="{Binding Source={StaticResource itemsViewSource}}"
            ItemTemplate="{StaticResource Standard250x250ItemTemplate}"
            SelectionMode="None"
            IsSwipeEnabled="false"
            IsItemClickEnabled="True"
            ItemClick="ItemView_ItemClick"/>

         <Button Hello />  <!-- From here come the Error -->           
    </ScrollViewer>
</Grid>

When I add any thing after my GridView, it give me that error (the property content is set more than once).

Answer 1

The answer is right there in the error message. A ScrollViewer can only have one child (you have two, a GridView and a Button). If you want to add multiple things, you will have to wrap them in a panel that allows multiple children (e.g. Grid).