Moving from WPF 3.5 to 4.0 causes error "Can't put a page in a Style"

Question

I'm in the process of moving my application from .NET 3.5 to .NET 4.0, and I get the following error message : "Can't put a page in a Style". I've implemented the MVVM pattern for this application and use Data Templates to tell the application how to render my various view models...for example below.

<DataTemplate DataType="{x:Type vm:ConfigureAxViewModel}">
    <vw:ConfigureAxPage />
</DataTemplate>

Is there any way around this error? Do I have to make my pages controls?

Thanks, Roy

I'n not surprised this doesn't work in 4.0, I'm confounded that it does in 3.5. Do I understand your question correctly? — Guge, Nov 25 '09 at 13:26
What's the misuderstanding? I defined a datatype as a page. I saw this in some MVVM tutorial a while back. — LPCRoy, Dec 01 '09 at 00:19

score 1 · Answer 1 · answered Aug 08 '12 at 22:44

Docs for both 3.5 & 4.0:

A page can be hosted from Window, NavigationWindow, Frame, or from a browser.

I would not expect a view that is a page to work in many instances for that matter, usually views are just UserControls. Though i also would not expect that error message...

score 0 · Answer 2 · edited May 23 '17 at 11:50

I happened to get this error in the designer in Visual Studio 2010. A couple of hours later with half of my hair gone, I found the problem in App.xaml

<DataTemplate DataType="{x:Type vm:LoginViewModel}">
     <views:Login />
</DataTemplate>

(So where is the "Style" they talk about???) Anyways, here, Login is a Page. It turns out a Page can't be used here. You have to specify a DataContext in the page's xaml instead:

DataContext="{Binding LoginPage,Source={StaticResource Locator}}

Source

I'm using MVVM Light so you might want to check it out for more information about the Locator.

Moving from WPF 3.5 to 4.0 causes error "Can't put a page in a Style"

2 Answers2