Question

I have a BackgroundWorker to call a function to do a long process at BackgroundWorker _DoWork, when error occur in the function I will prompt a customized messagebox:

 WPFMessageBoxResult result = WPFMessageBox.Show("Activation Fail", "Error!!", WPFMessageBoxButtons.OK, WPFMessageBoxImage.Error);

The exception below happens at WPFMessageBoxResult class :

The calling thread must be STA, because many UI components require this. 

Thank you.

Answer 1

You should not try to interact with any UI components from a background thread.

One way could be to catch the exception in your doWork method and assign it to the backgroundworker’s result property and then check if that result is a type of exception or not null if you are not using the result for anything else. then check for it in the backgroundWorker_completed event.

BackgroundWorker_DoWork(sender, )
{
    try
    {
       // do work        
    }
    catch (Exception ex)
    {
         BackgroundWorker w = sender as BackgroundWorker;
         if (w != null)
             w.Result = ex;
    }
}

then

BackgroundWorker_Completed()
{
    if (s.Result != null && e.Result is Exception)
    {
       Exception ex = e.Result as Exception;
       // do something with ex
    }
}