diff --git a/samples/ControlCatalog/Pages/ComboBoxPage.xaml b/samples/ControlCatalog/Pages/ComboBoxPage.xaml
index 369f703718..025b85492c 100644
--- a/samples/ControlCatalog/Pages/ComboBoxPage.xaml
+++ b/samples/ControlCatalog/Pages/ComboBoxPage.xaml
@@ -1,6 +1,7 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.ComboBoxPage">
+             x:Class="ControlCatalog.Pages.ComboBoxPage"
+             xmlns:sys="clr-namespace:System;assembly=netstandard">
   <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">ComboBox</TextBlock>
     <TextBlock Classes="h2">A drop-down list.</TextBlock>
@@ -35,6 +36,16 @@
            </DataTemplate>
          </ComboBox.ItemTemplate>
        </ComboBox>
+      
+      <ComboBox PlaceholderText="Pick an Item">
+        <ComboBoxItem>Inline Items</ComboBoxItem>
+        <ComboBoxItem>Inline Item 2</ComboBoxItem>
+        <ComboBoxItem>Inline Item 3</ComboBoxItem>
+        <ComboBoxItem>Inline Item 4</ComboBoxItem>
+        <DataValidationErrors.Error>
+          <sys:Exception /> 
+        </DataValidationErrors.Error>
+      </ComboBox>
     </StackPanel>
 
   </StackPanel>
diff --git a/src/Avalonia.Controls/Primitives/Popup.cs b/src/Avalonia.Controls/Primitives/Popup.cs
index becb489557..b445de0472 100644
--- a/src/Avalonia.Controls/Primitives/Popup.cs
+++ b/src/Avalonia.Controls/Primitives/Popup.cs
@@ -265,6 +265,7 @@ namespace Avalonia.Controls.Primitives
         /// <summary>
         /// Gets or sets the control that is used to determine the popup's position.
         /// </summary>
+        [ResolveByName]
         public Control? PlacementTarget
         {
             get { return GetValue(PlacementTargetProperty); }
diff --git a/src/Avalonia.Themes.Fluent/ComboBox.xaml b/src/Avalonia.Themes.Fluent/ComboBox.xaml
index 8155264f18..2eee656dc6 100644
--- a/src/Avalonia.Themes.Fluent/ComboBox.xaml
+++ b/src/Avalonia.Themes.Fluent/ComboBox.xaml
@@ -44,105 +44,107 @@
     <Setter Property="PlaceholderForeground" Value="{DynamicResource ComboBoxPlaceHolderForeground}" />
     <Setter Property="Template">
       <ControlTemplate>
-        <Grid RowDefinitions="Auto, *, Auto"
-              ColumnDefinitions="*,32">
-          <ContentPresenter x:Name="HeaderContentPresenter"
-                            Grid.Row="0"
+        <DataValidationErrors>
+          <Grid RowDefinitions="Auto, *, Auto"
+                ColumnDefinitions="*,32">
+            <ContentPresenter x:Name="HeaderContentPresenter"
+                              Grid.Row="0"
+                              Grid.Column="0"
+                              Grid.ColumnSpan="2"
+                              IsVisible="False"
+                              TextBlock.FontWeight="{DynamicResource ComboBoxHeaderThemeFontWeight}"
+                              Margin="{DynamicResource ComboBoxTopHeaderMargin}"
+                              VerticalAlignment="Top" />
+            <Border x:Name="Background"
+                    Grid.Row="1"
+                    Grid.Column="0"
+                    Grid.ColumnSpan="2"
+                    Background="{TemplateBinding Background}"
+                    BorderBrush="{TemplateBinding BorderBrush}"
+                    BorderThickness="{TemplateBinding BorderThickness}"
+                    MinWidth="{DynamicResource ComboBoxThemeMinWidth}" />
+
+            <Border x:Name="HighlightBackground"
+                    Grid.Row="1"
+                    Grid.Column="0"
+                    Grid.ColumnSpan="2"
+                    Background="{DynamicResource ComboBoxBackgroundUnfocused}"
+                    BorderBrush="{DynamicResource ComboBoxBackgroundBorderBrushUnfocused}"
+                    BorderThickness="{TemplateBinding BorderThickness}" />
+            <TextBlock x:Name="PlaceholderTextBlock"
+                       Grid.Row="1"
+                       Grid.Column="0"
+                       HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
+                       VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
+                       Margin="{TemplateBinding Padding}"
+                       Text="{TemplateBinding PlaceholderText}"
+                       Foreground="{TemplateBinding PlaceholderForeground}"
+                       IsVisible="{TemplateBinding SelectionBoxItem, Converter={x:Static ObjectConverters.IsNull}}" />
+            <ContentControl x:Name="ContentPresenter"
+                            Content="{TemplateBinding SelectionBoxItem}"
+                            ContentTemplate="{TemplateBinding ItemTemplate}"
+                            Grid.Row="1"
                             Grid.Column="0"
-                            Grid.ColumnSpan="2"
-                            IsVisible="False"
-                            TextBlock.FontWeight="{DynamicResource ComboBoxHeaderThemeFontWeight}"
-                            Margin="{DynamicResource ComboBoxTopHeaderMargin}"
-                            VerticalAlignment="Top" />
-          <Border x:Name="Background"
-                  Grid.Row="1"
-                  Grid.Column="0"
-                  Grid.ColumnSpan="2"
-                  Background="{TemplateBinding Background}"
-                  BorderBrush="{TemplateBinding BorderBrush}"
-                  BorderThickness="{TemplateBinding BorderThickness}"
-                  MinWidth="{DynamicResource ComboBoxThemeMinWidth}" />
-
-          <Border x:Name="HighlightBackground"
-                  Grid.Row="1"
-                  Grid.Column="0"
-                  Grid.ColumnSpan="2"
-                  Background="{DynamicResource ComboBoxBackgroundUnfocused}"
-                  BorderBrush="{DynamicResource ComboBoxBackgroundBorderBrushUnfocused}"
-                  BorderThickness="{TemplateBinding BorderThickness}" />
-          <TextBlock x:Name="PlaceholderTextBlock"
+                            Margin="{TemplateBinding Padding}"
+                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
+
+            <Border x:Name="DropDownOverlay"
+                    Grid.Row="1"
+                    Grid.Column="1"
+                    Background="Transparent"
+                    Margin="0,1,1,1"
+                    Width="30"
+                    IsVisible="False"
+                    HorizontalAlignment="Right" />
+
+            <Viewbox UseLayoutRounding="False"
+                     MinHeight="{DynamicResource ComboBoxMinHeight}"
                      Grid.Row="1"
-                     Grid.Column="0"
-                     HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
-                     VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
-                     Margin="{TemplateBinding Padding}"
-                     Text="{TemplateBinding PlaceholderText}"
-                     Foreground="{TemplateBinding PlaceholderForeground}"
-                     IsVisible="{TemplateBinding SelectionBoxItem, Converter={x:Static ObjectConverters.IsNull}}" />
-          <ContentControl x:Name="ContentPresenter"
-                          Content="{TemplateBinding SelectionBoxItem}"
-                          ContentTemplate="{TemplateBinding ItemTemplate}"
-                          Grid.Row="1"
-                          Grid.Column="0"
-                          Margin="{TemplateBinding Padding}"
-                          HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-                          VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
-
-          <Border x:Name="DropDownOverlay"
-                  Grid.Row="1"
-                  Grid.Column="1"
-                  Background="Transparent"
-                  Margin="0,1,1,1"
-                  Width="30"
-                  IsVisible="False"
-                  HorizontalAlignment="Right" />
-
-          <Viewbox UseLayoutRounding="False"
-                   MinHeight="{DynamicResource ComboBoxMinHeight}"
-                   Grid.Row="1"
-                   Grid.Column="1"
-                   IsHitTestVisible="False"
-                   Margin="0,0,10,0"
-                   Height="12"
-                   Width="12"
-                   HorizontalAlignment="Right"
-                   VerticalAlignment="Center">
-            <Panel>
-              <Panel Height="12"
-                     Width="12" />
-              <Path x:Name="DropDownGlyph"
-                    Stretch="Uniform"
-                    VerticalAlignment="Center"
-                    Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z" />
-            </Panel>
-          </Viewbox>
-          <Popup Name="PART_Popup"
-                 WindowManagerAddShadowHint="False"
-                 IsOpen="{TemplateBinding IsDropDownOpen, Mode=TwoWay}"
-                 MinWidth="{Binding Bounds.Width, RelativeSource={RelativeSource TemplatedParent}}"
-                 MaxHeight="{TemplateBinding MaxDropDownHeight}"
-                 PlacementTarget="{TemplateBinding}"
-                 IsLightDismissEnabled="True">
-            <Border x:Name="PopupBorder"
-                    Background="{DynamicResource ComboBoxDropDownBackground}"
-                    BorderBrush="{DynamicResource ComboBoxDropDownBorderBrush}"
-                    BorderThickness="{DynamicResource ComboBoxDropdownBorderThickness}"
-                    Margin="0,-1,0,-1"
-                    Padding="{DynamicResource ComboBoxDropdownBorderPadding}"
-                    HorizontalAlignment="Stretch"
-                    CornerRadius="{DynamicResource OverlayCornerRadius}">
-              <ScrollViewer HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
-                            VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}">
-                <ItemsPresenter Name="PART_ItemsPresenter"
-                                Items="{TemplateBinding Items}"
-                                Margin="{DynamicResource ComboBoxDropdownContentMargin}"
-                                ItemsPanel="{TemplateBinding ItemsPanel}"
-                                ItemTemplate="{TemplateBinding ItemTemplate}"
-                                VirtualizationMode="{TemplateBinding VirtualizationMode}" />
-              </ScrollViewer>
-            </Border>
-          </Popup>
-        </Grid>
+                     Grid.Column="1"
+                     IsHitTestVisible="False"
+                     Margin="0,0,10,0"
+                     Height="12"
+                     Width="12"
+                     HorizontalAlignment="Right"
+                     VerticalAlignment="Center">
+              <Panel>
+                <Panel Height="12"
+                       Width="12" />
+                <Path x:Name="DropDownGlyph"
+                      Stretch="Uniform"
+                      VerticalAlignment="Center"
+                      Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z" />
+              </Panel>
+            </Viewbox>
+            <Popup Name="PART_Popup"
+                   WindowManagerAddShadowHint="False"
+                   IsOpen="{TemplateBinding IsDropDownOpen, Mode=TwoWay}"
+                   MinWidth="{Binding Bounds.Width, RelativeSource={RelativeSource TemplatedParent}}"
+                   MaxHeight="{TemplateBinding MaxDropDownHeight}"
+                   PlacementTarget="Background"
+                   IsLightDismissEnabled="True">
+              <Border x:Name="PopupBorder"
+                      Background="{DynamicResource ComboBoxDropDownBackground}"
+                      BorderBrush="{DynamicResource ComboBoxDropDownBorderBrush}"
+                      BorderThickness="{DynamicResource ComboBoxDropdownBorderThickness}"
+                      Margin="0,-1,0,-1"
+                      Padding="{DynamicResource ComboBoxDropdownBorderPadding}"
+                      HorizontalAlignment="Stretch"
+                      CornerRadius="{DynamicResource OverlayCornerRadius}">
+                <ScrollViewer HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
+                              VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}">
+                  <ItemsPresenter Name="PART_ItemsPresenter"
+                                  Items="{TemplateBinding Items}"
+                                  Margin="{DynamicResource ComboBoxDropdownContentMargin}"
+                                  ItemsPanel="{TemplateBinding ItemsPanel}"
+                                  ItemTemplate="{TemplateBinding ItemTemplate}"
+                                  VirtualizationMode="{TemplateBinding VirtualizationMode}" />
+                </ScrollViewer>
+              </Border>
+            </Popup>
+          </Grid>
+        </DataValidationErrors>
       </ControlTemplate>
     </Setter>
   </Style>
@@ -232,4 +234,9 @@
   <Style Selector="ComboBox /template/ Border#HighlightBackground">
     <Setter Property="CornerRadius" Value="{DynamicResource ControlCornerRadius}" />
   </Style>
+  
+  <!-- Error State -->
+  <Style Selector="ComboBox:error /template/ Border#Background">
+    <Setter Property="BorderBrush" Value="{DynamicResource SystemControlErrorTextForegroundBrush}"/>
+  </Style>
 </Styles>