Why when navigating to a site using webbBrowser i'm getting null exception all the time?

Question

In constructor:

webBrowser2.Navigate("http://www.tapuz.co.il/forums/forumpage/393");

Then in DocumentCompleted:

void webBrowser2_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
        {
            HtmlElementCollection items = this.webBrowser1.Document.GetElementsByTagName("span");
            foreach (HtmlElement item in items)
            {
                if (item.GetAttribute("className") == "addMessage")
                {
                   item.InvokeMember("click");
                   break;
                }
            }
        }

I'm getting on

HtmlElementCollection items = this.webBrowser1.Document.GetElementsByTagName("span");

Null exception.

I tried to add before this line a loop:

while (webBrowser2.ReadyState != WebBrowserReadyState.Complete)
            {
                return;
            }

But then it didn't do anything when the page loaded. It's never got to to the next lines. I just saw the page loading in the webBrowser.

You are getting null reference exception because `this.webBrowser1.Document` is null. Because you navigated in `webBrowser2`. Also when using `DocumentCompleted` event you don't need such `while` loop. — Reza Aghaei, Dec 24 '15 at 13:48
A NRE is something that every developer hits at some point. The best thing you can do to arm yourself against it is learn how to debug - [this question](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) goes over it in a more general sense. — James Thorpe, Dec 24 '15 at 13:54
[What is a NullReferenceException and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Reza Aghaei, Dec 24 '15 at 13:55

Reza Aghaei · Accepted Answer · 2015-12-24T14:00:22.837

1

You are getting null reference exception because this.webBrowser1.Document is null.

Document property of WebBrowser is null before navigation.

You navigated in webBrowser2 and your webBrowser1.Document is still null.

edited Dec 24 '15 at 14:00

answered Dec 24 '15 at 13:54

Reza Aghaei

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Why when navigating to a site using webbBrowser i'm getting null exception all the time?

1 Answers1