Windows Service Webbrowser object invalid cast exception error

Question

Hi all,

I'm having a bit of trouble with a Windows Service webbrowser object. It's attempting to load in values of username and password to a site but keeps failing and throwing the following error:

System.InvalidCastException: Specified cast is not valid. at System.Windows.Forms.UnsafeNativeMethods.IHTMLDocument2.GetLocation() at System.Windows.Forms.WebBrowser.get_Document() at MyWindowsService.MyDataProcessor.login()

The code that I'm using to make this call is:

MyWebBrowser.Document.All["Login"].SetAttribute("Value", username);
            MyWebBrowser.Document.All["Password"].SetAttribute("Value", password);
            MyWebBrowser.Document.All["submit"].InvokeMember("Click");

Any ideas as to why it keeps failing? Thanks in advance for the help.

Answer 1

I'm not sure if this solves the problem, but you can check InvokeRequired property on the current object, or WebBrowser.InvokeRequired, and use something like MethodInvoker to call your function or a helper function to access WebBrowser.Document.

http://www.megasolutions.net/cSharp/(WebBrowser_Document-==-null)-throws-InvalidCastException-43126.aspx