'"Items collection must be empty before using ItemsSource."

I'm trying to get images to display in a WPF ListView styled like a WrapPanel as described in this old ATC Avalon Team article: How to Create a Custom View.

When I try to populate the ListView with a LINQ-to-Entities queried collection of ADO.NET Entity Framework objects I get the following exception:

Exception

Items collection must be empty before using ItemsSource.

My code…

Visual Basic

Private Sub Window1_Loaded(...) Handles MyBase.Loaded
    ListViewImages.ItemsSource = From g In db.Graphic _
                                 Order By g.DateAdded Ascending _
                                 Select g
End Sub

XAML

<ListView Name="ListViewImages"
          SelectionMode="Single"
          ItemsSource="{Binding}">
    <local:ImageView />
</ListView>

I put a breakpoint on that line. ListViewImages.ItemsSource is Nothing just before the LINQ assignment.

Solution 1:^[1]

I had this same error for a while in a slightly different scenario. The cause was invalid XAML, because some tags were missing.

I had

<wpftoolkit:DataGrid
    AutoGenerateColumns="False"
    ItemsSource="{Binding Path=Accounts}" >
    <wpftoolkit:DataGridTextColumn 
        Header="Account Name" 
        Binding="{Binding Path=AccountName}" />
</wpftoolkit:DataGrid>

which I fixed to be

<wpftoolkit:DataGrid
    AutoGenerateColumns="False"
    ItemsSource="{Binding Path=Accounts}" >
    <wpftoolkit:DataGrid.Columns>
        <wpftoolkit:DataGridTextColumn 
            Header="Account Name" 
            Binding="{Binding Path=AccountName}" />
    </wpftoolkit:DataGrid.Columns>
</wpftoolkit:DataGrid>

Solution 2:^[2]

I just ran into a VERY insidious example of this problem. My original fragment was much more complex, which made it difficult to see the error.

   <ItemsControl           
      Foreground="Black"  Background="White" Grid.IsSharedSizingScope="True"
      x:Name="MyGrid" ItemsSource="{Binding}">
      >
      <ItemsControl.ItemsPanel>
           <!-- All is fine here -->
      </ItemsControl.ItemsPanel>
      <ItemsControl.ItemTemplate>
           <!-- All is fine here -->
      </ItemsControl.ItemTemplate>
      <!-- Have you caught the error yet? -->
    </ItemsControl>

The bug? The extra > after the initial opening <ItemsControl> tag! The < got applied to the built-in Items collection. When the DataContext was later set, instant crashola. So look out for more than just errors surround your ItemsControl specific data children when debugging this problem.

Solution 3:^[3]

Me too on a different scenario.

<ComboBox Cursor="Hand" DataContext="{Binding}"  
              FontSize="16" Height="27" ItemsSource="{Binding}" 
              Name="cbxDamnCombo" SelectedIndex="0" SelectedValuePath="MemberId">

        <DataTemplate>
            <TextBlock DataContext="{Binding}">
                <TextBlock.Text>
                  <MultiBinding StringFormat="{}{0} / {1}">
                    <Binding Path="MemberName"/>
                    <Binding Path="Phone"/>
                  </MultiBinding>
                </TextBlock.Text>
            </TextBlock>
        </DataTemplate>

</ComboBox>

Now when you complete with the missing tag Control.ItemTemplate, everything gets to normal:

<ComboBox Cursor="Hand" DataContext="{Binding}"  
              FontSize="16" Height="27" ItemsSource="{Binding}" 
              Name="cbxDamnCombo" SelectedIndex="0" SelectedValuePath="MemberId">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock DataContext="{Binding}">
                <TextBlock.Text>
                  <MultiBinding StringFormat="{}{0} / {1}">
                    <Binding Path="MemberName"/>
                    <Binding Path="Phone"/>
                  </MultiBinding>
                </TextBlock.Text>
            </TextBlock>
        </DataTemplate>
    <ComboBox.ItemTemplate>
</ComboBox>

Solution 4:^[4]

I had this same error in a different scenario

<ItemsControl ItemsSource="{Binding TableList}">
    <ItemsPanelTemplate>
        <WrapPanel Orientation="Horizontal"/>
    </ItemsPanelTemplate>
</ItemsControl>

The solution was to add the ItemsControl.ItemsPanel tag before the ItemsPanelTemplate

<ItemsControl ItemsSource="{Binding TableList}">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <WrapPanel Orientation="Horizontal"/>
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
</ItemsControl>

Solution 5:^[5]

?? To state the answer differently ??

? In Xaml verify that there are no Missing Parent Nodes or incorrect nodes in the defined areas.

For example

This Is Failing:

There is no proper parent for the ItemsPanelTemplate child node below:

<ItemsControl ItemsSource="{Binding TimeSpanChoices}">
    <ItemsPanelTemplate>
        <UniformGrid Rows="1" />
    </ItemsPanelTemplate>
    ...
</ItemsControl>

This Is Working:

<ItemsControl ItemsSource="{Binding TimeSpanChoices}">
    <ItemsControl.ItemsPanel> <!-- I am the missing parent! -->
        <ItemsPanelTemplate>
            <UniformGrid Rows="1" />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    ...    
</ItemsControl>

? There is a proper parent node of <ItemsControl.ItemsPanel> provided^^^. ?

Solution 6:^[6]

Exception

Items collection must be empty before using ItemsSource.

This exception occurs when you add items to the ItemsSource through different sources. So Make sure you haven't accidentally missed a tag, misplaced a tag, added extra tags, or miswrote a tag.

<!--Right-->

<ItemsControl ItemsSource="{Binding MyItems}">
     <ItemsControl.ItemsPanel.../>
     <ItemsControl.MyAttachedProperty.../>
     <FrameworkElement.ActualWidth.../>
</ItemsControl>


<!--WRONG-->

<ItemsControl ItemsSource="{Binding MyItems}">
     <Grid.../>
     <Button.../>
     <DataTemplate.../>
     <Heigth.../>
</ItemsControl>

While ItemsControl.ItemsSource is already set through Binding, other items (Grid, Button, ...) can't be added to the source. However while ItemsSource is not in-use the following code is allowed:

<!--Right-->
<ItemsControl>
     <Button.../>
     <TextBlock.../>
     <sys:String.../>
</ItemsControl>

notice the missing ItemsSource="{Binding MyItems}" part.

Solution 7:^[7]

Keep template column inside DataGrid.Columns. This helped me resolve this issue.

Ref: DataGridTemplateColumn : Items collection must be empty before using ItemsSource.

Solution 8:^[8]

In my case, it was not using a DataTemplate for the ItemsControl.

Old:

<ItemsControl Width="243" ItemsSource="{Binding List, Mode=TwoWay}">
    <StackPanel Orientation="Horizontal">
        <TextBox Width="25" Margin="0,0,5,0" Text="{Binding Path=Property1}"/>
        <Label Content="{Binding Path=Property2}"/>
    </StackPanel>
</ItemsControl>

New:

<ItemsControl Width="243" ItemsSource="{Binding List, Mode=TwoWay}">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal">
                <TextBox Width="25" Margin="0,0,5,0" Text="{Binding Path=Property1}"/>
                <Label Content="{Binding Path=Property2}"/>
            </StackPanel>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

Solution 9:^[9]

In My case, it was just an extra StackPanel inside the ListView:

<ListView Name="_details" Margin="50,0,50,0">
            <StackPanel Orientation="Vertical">
                <StackPanel Orientation="Vertical">
                    <TextBlock Text="{Binding Location.LicenseName, StringFormat='Location: {0}'}"/>
                    <TextBlock Text="{Binding Ticket.Employee.s_name, StringFormat='Served by: {0}'}"/>
                    <TextBlock Text="{Binding Ticket.dt_create_time, StringFormat='Started at: {0}'}"/>
                    <Line StrokeThickness="2" Stroke="Gray" Stretch="Fill" Margin="0,5,0,5" />
                    <ItemsControl ItemsSource="{Binding Items}"/>
                </StackPanel>
            </StackPanel>
        </ListView>

Becomes:

<ListView Name="_details" Margin="50,0,50,0">
                <StackPanel Orientation="Vertical">
                    <TextBlock Text="{Binding Location.LicenseName, StringFormat='Location: {0}'}"/>
                    <TextBlock Text="{Binding Ticket.Employee.s_name, StringFormat='Served by: {0}'}"/>
                    <TextBlock Text="{Binding Ticket.dt_create_time, StringFormat='Started at: {0}'}"/>
                    <Line StrokeThickness="2" Stroke="Gray" Stretch="Fill" Margin="0,5,0,5" />
                    <ItemsControl ItemsSource="{Binding Items}"/>
                </StackPanel>
        </ListView>

and all is well.

Solution 10:^[10]

Mine was with a datagrid Style. If you leave out the <DataGrid.RowStyle> tags around the Style you get that problem. Weird thing is it worked for a while like that. Here is the bad code.

 <DataGrid Name="DicsountScheduleItemsDataGrid"
                  Grid.Column="0"
                  Grid.Row="2"
                  AutoGenerateColumns="false"
                  ItemsSource="{Binding DiscountScheduleItems, Mode=OneWay}">
            <Style TargetType="DataGridRow">
                <Setter Property="IsSelected"
                        Value="{Binding IsSelected, Mode=TwoWay}" />
            </Style>

and the good

 <DataGrid Name="DicsountScheduleItemsDataGrid"
                  Grid.Column="0"
                  Grid.Row="2"
                  AutoGenerateColumns="false"
                  ItemsSource="{Binding DiscountScheduleItems, Mode=OneWay}">
            <DataGrid.RowStyle>
            <Style TargetType="DataGridRow">
                <Setter Property="IsSelected"
                        Value="{Binding IsSelected, Mode=TwoWay}" />
            </Style>
            </DataGrid.RowStyle>

Solution 11:^[11]

I had the same error. The problem was this extra symbol ">" added by mistake between the tags </ComboBox.SelectedValue> and </ComboBox>:

<ComboBox 
   ItemsSource="{Binding StatusTypes}"
   DisplayMemberPath="StatusName"
   SelectedValuePath="StatusID">
   <ComboBox.SelectedValue>
      <Binding Path="StatusID"/>
   </ComboBox.SelectedValue>
   >
</ComboBox>

and here is the correct code:

<ComboBox 
   ItemsSource="{Binding StatusTypes}"
   DisplayMemberPath="StatusName"
   SelectedValuePath="StatusID">
   <ComboBox.SelectedValue>
      <Binding Path="StatusID"/>
   </ComboBox.SelectedValue>
</ComboBox>

Solution 12:^[12]

I've had this error when I tried applying context menus to my TreeView. Those tries ended up in a bad XAML which compiled somehow:

<TreeView Height="Auto" MinHeight="100"  ItemsSource="{Binding Path=TreeNodes, Mode=TwoWay}" 
    ContextMenu="{Binding Converter={StaticResource ContextMenuConverter}}">
    ContextMenu="">
    <TreeView.ItemContainerStyle>
    ...

Note the problematic line: ContextMenu=""> .
I don't know why it compiled, but I figured it's worth mentioning as a reason for this cryptic exception message. Like Armentage said, look around the XAML carefully, especially in places you've recently edited.

Solution 13:^[13]

I encountered this error in another situation. I tried to defined a style for TreeViewItems directly within the <TreeView>, but instead should have embedded that within <TreeView.ItemContainerStyle>.

Wrong:

<TreeView ItemsSource="{Binding ExampleListView}">
    <Style TargetType="{x:Type TreeViewItem}">
        <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}"/>
        <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}"/>
    </Style>
    <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding SubItemListList}">
        ...
        </HierarchicalDataTemplate>
    </TreeView.ItemTemplate>
</TreeView>

Correct:

<TreeView ItemsSource="{Binding ExampleListView}">
    <TreeView.ItemContainerStyle>
        <Style TargetType="TreeViewItem">
            <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}"/>
            <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}"/>
        </Style>
    </TreeView.ItemContainerStyle>
    <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding SubItemListList}">
        ...
        </HierarchicalDataTemplate>
    </TreeView.ItemTemplate>
</TreeView>

Solution 14:^[14]

I ran into this problem because one level of tag, <ListView.View> to be specirfic, was missing in my XAML.

This code produced this error.

<Grid>
    <ListView Margin="10" Name="lvDataBinding" >
        <GridView>
            <GridViewColumn Header="Name" Width="120" DisplayMemberBinding="{Binding Name}" />
            <GridViewColumn Header="Age" Width="50" DisplayMemberBinding="{Binding Age}" />
            <GridViewColumn Header="Mail" Width="150" DisplayMemberBinding="{Binding Mail}" />
        </GridView>
    </ListView>
</Grid>

The following fixed it

<Grid>
    <ListView Margin="10" Name="lvDataBinding" >
        <ListView.View> <!-- This was missing in top! -->
            <GridView>
                <GridViewColumn Header="Name" Width="120" DisplayMemberBinding="{Binding Name}" />
                <GridViewColumn Header="Age" Width="50" DisplayMemberBinding="{Binding Age}" />
                <GridViewColumn Header="Mail" Width="150" DisplayMemberBinding="{Binding Mail}" />
            </GridView>
        </ListView.View>
    </ListView>
</Grid>

Solution 15:^[15]

Perhaps not such an useful answer, but I had the same problem when changing column order and made mistake like the one in the following sample. Having a lot of columns, I reordered them and somehow pasted one after closing tag /DataGrid.Columns:

       <DataGridTemplateColumn x:Name="addedDateColumn" Header="Added Date" Width="SizeToHeader">
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding Path=AddedDate}" />
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>
            </DataGridTemplateColumn>
        </DataGrid.Columns>
            <DataGridTemplateColumn x:Name="rowguidColumn" Header="rowguid" Width="SizeToHeader">
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding Path=rowguid}" />
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>
            </DataGridTemplateColumn>
    </DataGrid>

Anyway, lost half an hour because of this. Hope this helps others.

Solution 16:^[16]

There are many possible reasons for getting this error. In my case, I was adding a datagrid column outside the 'columns' tag. like displayed in image. Surpisingly there was no error given by XAML editor.

Solution 17:^[17]

Beware of typos! I had the following

<TreeView ItemsSource="{Binding MyCollection}">
    <TreeView.Resources>
        ...
    </TreeView.Resouces>>
</TreeView>

(Notice the tailing >, which is interpreted as content, so you're setting twice the content... Took me a while :)

Solution 18:^[18]

I had the very same error.
In my case, i just removed a single line <UniformGrid Columns="3" />

<ListBox>
    <UniformGrid Columns="3" /> // remove this line!!!!
    ...
</ListBox>

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	StayOnTarget
Solution 2	Ben Voigt
Solution 3	Junior MayhÃ©
Solution 4	Massimiliano Kraus
Solution 5
Solution 6
Solution 7	Community
Solution 8	samiz
Solution 9	Carl
Solution 10	PatFromCanada
Solution 11
Solution 12	Noich
Solution 13	RonnyR
Solution 14	zar
Solution 15	Andrei Floroiu
Solution 16	Himanshu Mange
Solution 17	ElGauchooo
Solution 18	Pixel_95

'"Items collection must be empty before using ItemsSource."

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]

This Is Failing:

This Is Working:

Solution 6:[6]

Solution 7:[7]

Solution 8:[8]

Solution 9:[9]

Solution 10:[10]

Solution 11:[11]

Solution 12:[12]

Solution 13:[13]

Solution 14:[14]

Solution 15:[15]

Solution 16:[16]

Solution 17:[17]

Solution 18:[18]