WPF The refrence is invalid or unsupported

Question

Hi dears,
I want to add System.Windows.Forms.dll to my project but it get an error The refrence is invalid or not supported.
my project : WPF .net 6/C#/32bit

I want to use WindowsFormsHost control

<PropertyGroup>  
    <OutputType>WinExe</OutputType>  
    <TargetFramework>net6.0-windows</TargetFramework>  
    <UseWPF>True</UseWPF>  
    <UseWindowsForms>True</UseWindowsForms>  
    <ApplicationIcon>AppIcon.ico</ApplicationIcon>  
    <PlatformTarget>x86</PlatformTarget>  
    <PackageIcon></PackageIcon>  
    <ApplicationManifest>app.manifest</ApplicationManifest>  
    <RunAnalyzersDuringBuild>True</RunAnalyzersDuringBuild>  
  </PropertyGroup>  

Answer 1

Hi, @hossein tavakoli . Welcome Microsoft Q&A.
I am testing with the code below and it works. Could the error be caused by something else?

<Project Sdk="Microsoft.NET.Sdk">  
  <PropertyGroup>  
    <OutputType>WinExe</OutputType>  
    <TargetFramework>net6.0-windows</TargetFramework>  
	  <UseWPF>True</UseWPF>  
	  <UseWindowsForms>True</UseWindowsForms>  
	  <PlatformTarget>x86</PlatformTarget>  
	  <PackageIcon></PackageIcon>  
	  <RunAnalyzersDuringBuild>True</RunAnalyzersDuringBuild>  
    <Platforms>AnyCPU;ARM32</Platforms>  
  </PropertyGroup>  
</Project>  

<Grid>  
        <WindowsFormsHost x:Name="host" Width="300" Height="300">  
        </WindowsFormsHost>  
    </Grid>  
 public partial class MainWindow : Window  
    {  
        MaskedTextBox mtb = new MaskedTextBox("00/00/0000");  
        ToolTip tt=new System.Windows.Forms.ToolTip();  
        public MainWindow()  
        {  
            InitializeComponent();  
            mtb.Width = 200;  
            mtb.Height=  100;  
            mtb.MaskInputRejected += new MaskInputRejectedEventHandler(maskedTextBox1_MaskInputRejected);  
            mtb.KeyDown += new KeyEventHandler(maskedTextBox1_KeyDown);  
            host.Child = mtb;  
        }  
        void maskedTextBox1_MaskInputRejected(object sender, MaskInputRejectedEventArgs e)    {    ...    }  
        void maskedTextBox1_KeyDown(object sender, KeyEventArgs e)    {  tt.Hide(mtb); }  
    }