Type reference cannot find public type named

Question

I am getting error like "Type reference cannot find public type named 'Sign'" in xaml. how can i resolve it. the Sign class is in the same assembly.

<DataTemplate DataType="{x:Type local:Sign}">
    <Expander Padding="4"
              IsExpanded="{Binding RelativeSource={
                    RelativeSource Mode=FindAncestor, AncestorType={
                       x:Type ListBoxItem}}, Path=IsSelected}">
        <Expander.Header>
            <TextBlock Text="{Binding Name}" ... />
        </Expander.Header>
        <DockPanel LastChildFill="True">
            <Border DockPanel.Dock="Left" CornerRadius="16" BorderBrush="WhiteSmoke" Background="AliceBlue" BorderThickness="5" HorizontalAlignment="Center" VerticalAlignment="Center">
                <Image Source="{Binding Icon}" Width="90" Height="90" Stretch="Fill" />
            </Border>
            ...
        </DockPanel>                
    </Expander>

Answer 1

If the type resides in the same assembly as the XAML you are modifying, omit the assembly segment of the clr-namespace when you import the namespace.

DO

xmlns:local="clr-namespace:NamespaceContainingSignClass"

DO NOT

xmlns:local="clr-namespace:NamespaceContainingSignClass;assembly=AssemblyContainingSignClassAndXAML"

Answer 2

For those in my boat who weren't helped by the top 1,00 results for this error on Google....in my case it was the precise opposite of the advice from smelch: i had to ADD the assembly info on the end of my xmlns declaration. Likely because of my particular circumstances, i guess - my datatemplate was in a stand-alone resourcedictionary xaml file. Not sure. I just know it didn't work until i added the assembly info, so for those floundering out there give that a whack and see if it works. i'm not inclined to dive into why, it just did.

Answer 3

1. Check if the root tag of the xaml file has the namespace with class Sign mapped to local alias: xmlns:local="clr-namespace:NamespaceContainingSignClass"
2. Check whether class Sign is marked public
3. Check whether class Sign has parameterless constructor

Answer 4

1. Go through and check all of the answers to this question - I'm sure one of them is right, but I don't know which one worked for me.
2. Save your project, close Visual Studio, re-open Visual Studio.
3. Voila, it now magically works, despite not changing anything.
4. Swear at Microsoft under your breath, and carry on with your life...

Answer 5

I just discovered another issue, that may cause this problem. It is allowed to use dots in project names, eg

FancyTrainsimTools.Desktop

is a valid project name. If you use folders in the project, you may get constructs like this:

FancyTrainsimTools.Desktop.Logic

If you define data templates referencing items in this folder, this results in error messages. I also used a hierarchical datatemplate, but this gives slightly different messages.

The workaround:

Rename your project by removing the dot:

FancyTrainsimToolsDesktop

Edit: I try to reproduce the issue again, in order to report a bug, but now it all works.... So mystery not yet solved and not clear what to do to create w ork around....

Answer 6

Ran into this error right now. The problem was that the class I was referencing from my assembly was in an assembly that had a higher framework level(4.7.2 against 4.6). Version alignment solved the problem.