Cannot create unknown type '{CLR -- error in WPF

Question

Hi,

I am working on one WPF application. In this I am loading main window XAML in run time and Application_Start event.

I the main window I am initializing an object in Window.Resource.

<Window 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:data="clr-namespace:ExpnseManager.DataAccess"
        Title=".::Expense Manager::." Height="750" Width="750">
    <Window.Resources>
        <data:ExpesneManagerDataAccess x:Key="aa" />
    </Window.Resources>

Here I am getting error - Cannot create unknown type '{CLR

Answer 1

Check whether ExpesneManagerDataAccess class is available in ExpnseManager.DataAccess. There could be some mistake in typing.

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Gaurav Khanna | Microsoft VB.NET MVP

Answer 2

xmlns:data="clr-namespace:ExpnseManager.DataAccess"

<data:ExpesneManagerDataAccess x:Key="aa" />

Expesne or Expnse, they are different.

---

Sheldon _Xiao[MSFT]
MSDN Community Support | Feedback to us
Microsoft
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 3

Hi Gaurav,

Problem is not with the typing spelling, otherwise it wont compile.

However I have checked all spellings and corrected as it was creating confusion.

Thanks,

Nitin

Answer 4

Hi,

ExpnseManager.DataAccess is the namespace.

ExpesneManagerDataAccess is the class under this namespace.

Thanks,

Nitin

Answer 5

Hi,

Is the ExpenseManager.DataAccess in another project? If it is then you need to change your reference to add that information -

xmlns:data="clr-namespace:ExpnseManager.DataAccess;assembly=AssemblyName"

Answer 6

It is in same project.

Answer 7

It doesn't sound as though you have a peroblem referencing the class. Have you tried to debug into the ExpesneManagerDataAccess to see if anything in there is causing an exception?

Answer 8

Hi,

I tried that, in fact I tried with just empty class, it is not working.

And one more thing if I don't load XAML in run time i.e. using StartUpURI in App.Config , it is working.

In my project I have deleted the Main.Xaml.cs class and loading main.xaml in run time from Application_start event and in main.xaml intializing this class(ExpesneManagerDataAccess ) instance.

I hope it clears my problem.

Thanks,

Nitin

Answer 9

Hi Nitin,

I still cannot reproduce the issue. Could you please share a minimum about this issue so that we can reproduce the issue locally?

Thank you!

---

Min Zhu [MSFT]
MSDN Community Support | Feedback to us

Answer 10

Below Steps:

1. Create a new WPF Project

2. Delete MainWindow.xaml.cs (Code Behind Class)

3. Delete this class reference from MainWindow.xaml file( Just beside <Window tag in MainWindow.xaml)

4. Open App.xaml, replace StartUri with StartUp event

Startup="Application_Startup"

5. In the App.xaml.cs

private void Application_Startup(object sender, StartupEventArgs e)
 {
       Window window = XamlReader.Load(new FileStream(@"MainWindow.xaml",FileMode.Open)) as Window;
       window.Show();

 }

6. Run the code it works fine.

7. Now add a new folder in Project say DataAccess

8. Add a new class in this folder say DataManager or whatever name you give.

9. Create this instance MainWindow.xaml

<Window 
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:data="clr-namespace:TestDeleteApp.DataAccess"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <data:TestDataAccess x:Key="a" />
    </Window.Resources>

10. Now run the application, it gives error.

Answer 11

Hi Nitin,

This makes your xaml file become "loose xaml". And you can no longer omit the assembly name in the namespace mapping.

xmlns:data="clr-namespace:TestDeleteApp.DataAccess;assembly=AssemblyName"

Best regards,

---

Min Zhu [MSFT]
MSDN Community Support | Feedback to us

Answer 12

Wow!! It worked. Thanks :)