Could not load file or assembly Microsoft.Xaml.Behaviors

Describe the bug Using behaviors in my xaml brings compilation error message.

To Reproduce

<Window x:Class="Aveva.SplashScreen.Sample.View.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:b="http://schemas.microsoft.com/xaml/behaviors"
        >
    <b:Interaction.Triggers>
        <b:EventTrigger EventName="MouseDown" >
            <b:InvokeCommandAction 
                Command="{Binding MouseDownCommand}" 
                CommandParameter="{Binding Mode=OneWay, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window }}"  />
        </b:EventTrigger>
    </b:Interaction.Triggers>

Error

System.Windows.Markup.XamlParseException: 'Could not load file or assembly 'Microsoft.Xaml.Behaviors, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.'

Expected behavior To work out of the box, without having to reference library in code behind. Because it works fine if I reference anything:

        public MainWindow()
        {
            InitializeComponent();
            
            var _ = new Microsoft.Xaml.Behaviors.DefaultTriggerAttribute(typeof(Trigger), typeof(Microsoft.Xaml.Behaviors.TriggerBase), null);
        }

Desktop (please complete the following information):

Version with bug: 1.1.31

Issue Analytics

State:
Created 3 years ago
Reactions:5
Comments:9

Top GitHub Comments

4reactions

Jebarsoncommented, Feb 3, 2021

This a repro for me. It happens when the Page is in a class library. The easiest workaround is to name behavior command in the xaml.

<Behaviors:InvokeCommandAction x:Name="SelectionCommand" Command="{Binding SelectedItemsChangedCommand}"

3reactions

jerrudcommented, Dec 23, 2021

I have the OPs same problem using version 1.1.39. The view is simply a Window in a folder in a class library. The library is a plug-in for another application. Creating a new WPF application and loading in that app as a plugin to the host app does not have this exception.

I was able to use OPs work around and view now works:

        public MainWindow()
        {
            InitializeComponent();
            
            var _ = new Microsoft.Xaml.Behaviors.DefaultTriggerAttribute(typeof(Trigger), typeof(Microsoft.Xaml.Behaviors.TriggerBase), null);
        }