"The calling thread must be STA, because many UI components require this" error when creating a WPF pop-up Window in thread

Solution 1:

For the thread that you're trying to start the GUI element in, you need to set the apartment state of the thread to STA BEFORE you start it.

Example:

myThread.SetApartmentState(ApartmentState.STA);
myThread.Start();

Solution 2:

Absolutely Dispatcher is only way to do something (in specific Thread) when we work with multi-threading in WPF!

But for work with Dispatcher we must know 2 things:

1. Too many way to use Dispatcher like Dispatcher_Operation , [window.dispatcher] or etc.
2. We must call dispatcher in the main thread of app (that thread is must be STA thread)

So for example: if we want show other window[wpf] in another thread, we can use this code:

Frmexample frmexample = new Frmexample();
            frmexample .Dispatcher.BeginInvoke //Updated the variable name
                (System.Windows.Threading.DispatcherPriority.Normal,
                (Action)(() =>
                {
                    frmexample.Show();
                    //---or do any thing you want with that form
                }
                ));

Tip: Remember - we can't access any fields or properties from out dispatcher, so use that wisely