Hi,

You can not do this this way using async which would use an internal thread pool thread that you have no control over with. Because EO.WebControl maintains thread specific resources such as window handles, Windows requires these handles must be destroyed in the same thread in which they were created. So you can not simply use async to create them and then forget about it. You MUST come back to clean up in the same thread at a later time --- we do have some automatic clean up code that can do this for you but only if the original thread is still around and is still actively pumping Windows messages, which obviously would not be the case for a thread pool thread.

To avoid such problem, you will need to avoid using async to create the WebControl control. If you must create the control in a different thread, you can create a separate thread, create the WebControl (along with the containing Form) and then call Application.Run to run that Form. The thread will then terminate when the Form closes.

Thanks!

Yes. That works too. The key is you must dispose the form once it is closed in that thread.