CODEWITHSUNDEEP
uwp
NPadrutt
NPadrutt

Reputation: 4257

UWP System.InvalidCastException: Unable to cast COM object

I have an UWP App targeting the FCU. Since today I get the following exception:

System.InvalidCastException: Unable to cast COM object of type 'System.__ComObject' to class type 'System.String'. Instances of types that represent COM components cannot be cast to types that do not represent COM components; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface.
   at MoneyFox.Windows.Views.AccountListView.AccountListView_obj1_Bindings.Update_CurrentBalance(Double obj, Int32 phase)
   at MoneyFox.Windows.

As far as I can see it happens as soon as a binding with the type double to a TextBlock should update. But I haven't changed anything on that code.

I have the latest VS 15.7.3. Also I made tries with targeting different platforms and different versions of Microsoft.NETCore.UniversalWindowsPlatform (currently 6.0.8).

The Link to the repository: https://github.com/NPadrutt/MoneyFox.Windows/tree/XamarinFormsNew

What can that be?

Upvotes: 0

Views: 390

Answers (1)

NPadrutt
NPadrutt

Reputation: 4257

I found the issue.. I have a converter who implements IValueConverter by Xamarin.Forms as well as inherits from MvxValueConverter so I can use it for Xamarin Forms Bindings aswell as with my UWP app withouth XF.

public class AmountFormatConverter : MvxValueConverter, IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        // Converter Logic
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) 
    {
        // Convert Back Logic
    }
}

My issue here was, that I didn't set the the Override keyword for the implemented methods. It seems that caused the issue.

public class AmountFormatConverter : MvxValueConverter, IValueConverter
{
    public override object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        // Converter Logic
    }

    public override object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) 
    {
        // Convert Back Logic
    }
}

Upvotes: 2

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