Catel call ShowDialogAsync sync

I try to call ShowDialogAsync in a synchron code. I'm not very familiar with async programming. If I run this code, I end up in a deadlock. If I change Command to TaskCommand, it will work, but I have to change all Code to async.

    public MainWindow()
    {
        InitializeComponent();
        Abc = new Command(() => Asd());
    }

    public Command Abc { get; set; }

    private void Asd()
    {
        var b = StartDialog(true).GetAwaiter().GetResult();
    }

    private async Task<bool> StartDialog(bool isMultiple)
    {
        await ServiceLocator.Default.ResolveType<IUIVisualizerService>().ShowDialogAsync<PersonVm>(new PersonM());
        return true;
    }

Here I have used the answer from here. Could someone help me please?

The recommended way is to migrate your code to async. Most features in Catel are async (such as vm initialization, etc). At first it might be a bit overwhelming, but once you get how it works, it's a very convenient way of programming. In the meantime, you can use a workaround (this is not best practice, but will get you through this task):

    private async void Asd()
    {
        var b = await StartDialog(true);
    }

Note that async void is not recommended and should really be avoided unless no other options are available (such as non-async event handlers, etc).