Cannot find resource dictionary in WPF application

Question

I'm in the process of building a WPF application and ran into an error when trying to reference a resource dictionary. Inside my WPF application project I have a folder called "Styles" to contain all the xaml style templates for my app:

In my app.xaml file I have this:

<Application.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="Styles/MetroTheme.xaml" />
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</Application.Resources>

However, when I hover over the source property I get an error saying "An error occurred while finding the resource dictionary "Styles/MetroTheme.xaml". I can see the xaml file inside the folder both in Visual Studio and in the file system.

I have also tried "/Styles/MetroTheme.xaml" and a pack uri for the source property, both with no success. Any idea why I'm getting this file not found error?

Answer 1

Make sure that the build action for MetroTheme.xaml is set to Page.

Answer 2

I had the same issue, but setting Build Action = Page did not solve for me. Turned out I needed to use the Pack URI Format. So,

<ResourceDictionary Source="pack://application:,,,/Styles/MetroTheme.xaml"/>

EDIT

Turns out the above will eliminate build error but still results in runtime error. I needed to include full assembly specification for complete resolution (even though all files are in same assembly):

<ResourceDictionary Source="pack://application:,,,/WpfApplication10;component/Styles/MetroTheme.xaml"/>