Hi all,

I have an in interesting problem I am hoping someone can help with. I have an Umbraco 4.7 based site that uses usercontrols to add server side functionality to the site, forming a web application. During the development, there were no issues. About two months after the site went live, we randomly started seeing exceptions. Restarting the IIS service fixed it.

Months after that, we are seeing these errors more and more frequently - almost every day now. Restarting the IIS service *usually* but not always fixes it, and who knows when it's going to go down again. The stack trace points to the null reference happening within one of my user controls, but it's a control that should not be executed when the user first enters the URL - only when they click a link to that page.

So the sequence goes like this:
1. User enters base URL
2. User gets error.
3. Stack trace looks like this:

Exception information: 
    Exception type: NullReferenceException 
    Exception message: Object reference not set to an instance of an object.
   at payStubList.Page_Load(Object sender, EventArgs e) in payStubList.ascx.vb:line 10
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

The reason that generates a null reference is because the code in that page was only meant to be run after login. It expects to be able to create a MembershipUser object. However that code is being run immediately when the user hits the site, prior to logging in... intermittently. I know this isn't much to go on, but I wonder if anyone else has seen anything like this?

This is hosted on a dedicated Windows 2008 server.

Thanks,
Joe