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What I tried:
I tried to add this to the custom master page (just before the closing form tag):
It didn't work. I saw no difference in the source html. And I noticed that the form digest information was always there, regardless.
I also tried to add to the existing code behind of the custom master page:
protected override void OnInit(EventArgs e)
{
if (Page.IsPostBack) // custom stuff
{
Microsoft.SharePoint.Utilities.SPUtility.ValidateFormDigest();
}
It didn't work.
I tried to remove my customized master page and to use an out-of-the-box SharePoint master page. The problem was still there. I then tried to use an out-of-the-box page layout. The problem was still there. I tried to create a brand new out-of-the-box web application. The problem was not there. I then went back to web site where the problem was happening and began to comment out the http modules in web.config - trying different combinations to isolate the HTTP module. And I zoomed in to one module. I also changed the order of the http modules. Still, the same http module was the one.
Even after I found the faulty http module, it was not easy to isolate the problem. I had to comment out the different conditions until I isolated SPContext.Current.
Even after I found the faulty http module, it was not easy to isolate the problem. I had to comment out the different conditions until I isolated SPContext.Current.
Solution:
( It depends on your environment... It may not be applicable to you )
Changing the HTTP module so that the evaluation of SPContext.Current only happens after the verification that the current handler is a Page. :
public class MyMengaoModule : IHttpModule
public void Init(HttpApplication context){
context.PreRequestHandlerExecute +=
new EventHandler(ContextPreRequestHandlerExecute);
}
void ContextPreRequestHandlerExecute(object sender, EventArgs e)
{
Page page = HttpContext.Current.CurrentHandler as Page; // new stuff
if (page == null)
{
return;
}
if (SPContext.Current != null && SPContext.Current.Site != null && SPContext.Current.Site.Zone == SPUrlZone.Internet) // as it was before
...
Time it took me to fix the problem: 3 days of work...