Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead. Error while parsing XAML

Question

I get a runtime error that crashes when it tries to parse my XAML.

<TreeViewItem Header="{Binding Header}" ItemsSource="{Binding DataGroups}">
    <ListView ItemsSource="{Binding DataGroups}">
        <ListView.View>
            <GridView>
                <GridViewColumn Header="Group Name" DisplayMemberBinding="{Binding Path=Name}" />
                <GridViewColumn Header="Group Type" DisplayMemberBinding="{Binding Path=Type}" />
            </GridView>
        </ListView.View>
    </ListView>
</TreeViewItem>

score 0 · Accepted Answer · edited Jul 22 '13 at 01:11

After searching through all the questions related to this, I couldn't find the answer. Most involved people changing the Items property on the TreeViewItem, which will throw this error.

In my case, I didn't change anything.

However, if you notice.

<TreeViewItem Header="{Binding Header}" ItemsSource="{Binding DataGroups}">
    <ListView ItemsSource="{Binding DataGroups}">

I have bound to the same collection twice.

So, double check you haven't bound to the same collection twice if you get this error.

Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead. Error while parsing XAML

1 Answers1