WPF中Button.Content上的System.InvalidOperationException

Question

Probably a stupid thing but I found the answer nowhere...

I have the following code in my C# WPF Project:

string timer = "5:00"; 
Button.Content = timer;

and it gives me System.InvalidOperationException once code execution reaches this point. It also doesn't work with Button.Content = "5:00"; but funny enough in another function this code

string newLabel = Math.Floor(timerSec / 60f).ToString() + ":" + (timerSec % 60).ToString("0#");
Button.Content = newLabel;

works just fine. What am I missing?

//edit: the question cause confusion because it is pseudo code and I didn't think too much when I put it. here is how the button is actually defined:

<Viewbox Grid.Row="1" Grid.Column="0">
     <Button x:Name="_5v5OwnBlueButton" Content="5:00" Margin="5" />
</Viewbox>

Answer 1

Are you using threads?

Try this:

string timer = "5:00"; 
     this.Dispatcher.Invoke(DispatcherPriority.Normal, (Action) () => 
            {

              Button.Content = timer;
            });