asp.net unhandled exception

Question

I have an application that has been running in produciton for a while now, and every now and then it throws an akward exception that I catch in the global.asax session error event. This procedure sends an email out with the error message, source, and stack of the error, and that is usually sufficient information for us to find the problem. However, this particular error does not have the entire stack. It apparently dies before it gets to my application in the stack.

Below is the information that is sent to me in an email. Through some other logging within my application, I can find which page it is occuring, but without the stack showing any of my application's code, I really don't know where to start. Any help here would be greatly appreciated.

Error Info:

Message: Object reference not set to an instance of an object.

Source: System.Web

Stack:

at System.Web.UI.WebControls.ImageButton.RaisePostBackEvent(String eventArgument)

at System.Web.UI.WebControls.ImageButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)

at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)

at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)

at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Answer 1

Are there any complaining users?

Wouldn't bother otherwise-- this might be triggered by a robot browser, or a user cancelling his request at an unexpected point, and many other reasons.

Answer 2

I would start looking at the page that threw the error, then look at the various image button controls that you have. My guess would be a dynamically loaded control, that was not reloaded.

We can't say much until we see the code