designer shows A 'Binding' can only be set on a DependencyProperty of a DependencyObject error

Question

I've created a user control that has a DependencyProperty, and when I try binding to it I get an error in the designer:

" 'Binding' cannot be set on the 'ROCValue' property of type 'RocIndicator'. A 'Binding' can only be set on a DependencyProperty of a DependencyObject.

Edit: I've added the static modifier, but I still get that error. and yes, I've restarted visual studio.

public partial class RocIndicator : UserControl
{
    public static readonly DependencyProperty ROCValueProperty =
        DependencyProperty.Register("ROCValue", typeof(double), typeof(RocIndicator),
        new FrameworkPropertyMetadata(0.0, new PropertyChangedCallback(ValueChanged)));


    public double ROCValue
    {
        get { return (double)GetValue(ROCValueProperty); }
        set { SetValue(ROCValueProperty, value); }
    }
}

this is the XAML:

<View:RocIndicator ROCValue="{Binding ROC}" Margin="0,10,0,0" HorizontalAlignment="Center" Width="35"/>

but when I build & run it works. why is this error showing?

Answer 1

Dependency property declaration must be static:

public static readonly DependencyProperty ROCValueProperty ...

Answer 2

I had the same issue once when copying a UserControl from one project to another. I tried closing the solution, restarting Visual Studio and even restarting my PC. None of those worked.

I then unloaded and reloaded the project and this seemed to fix it. (Potentially a Visual Studio build bug).

To unload the project, right click on your project in Solution Explorer and click 'Unload Project'. Then right click again and click 'Reload Project'.