Object reference not set to an instance of an object when setting up an alert

Question

I have a user trying to setup an alert whenever any item changes in a document library. Whenever they try to do so SharePoint throws the following error:

Object reference not set to an instance of an object. at Microsoft.SharePoint.ApplicationPages.SubNewEditBasePage.SetAlertProperties(SPAlert a, SPWeb web, SPList list, String strAlertTemplateName, RadioButtonList RadioBtnEventType, RadioButtonList RadioBtnAlertFreq, RadioButtonList RadioBtnAlertFilter, TextBox TextTitle, DropDownList DdlView) at Microsoft.SharePoint.ApplicationPages.SubNewPage.BtnCreateAlert_Click(Object sender, EventArgs e) at System.Web.UI.WebControls.Button.OnClick(EventArgs e) at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

I've tried removing all of their other alerts, naming the new alert various ways, and even setting up multiple alerts (one for when items are created, one for when they are modified). Unfortunately this error comes up on every attempt.

What could be causing this?

Answer 1

Have you changed anything in sharepoint designer that you migh of removed?

Cause:
This error occurs because the discussion board, list, or document libraries original dispform.aspx was deleted using SharePoint designer. We have some dependencies on the original dispform.aspx so if this is ever deleted within SharePoint designer, this problem will occur.

Resolution:
The best resolution is to restore the problem discussion board, list, or document library prior to when the deletion occurred. The other method is to move the items to a new library. A variety of options are available to move data over. The object model can be leveraged or the items can be moved over via Manage Content and Structure. While these methods work fine for Lists and Document libraries, discussion boards are a little more challenging. I found the easiest way to move Discussion board items was using Outlook.

http://blogs.msdn.com/b/russmax/archive/2010/10/22/plan-to-delete-any-oob-dispform-aspx-pages-in-sharepoint-designer.aspx

hope it helps :)

Answer 2

This error 99% of the time is due to an item, list or library not being present but having a reference to it.

In this case, it is because the alerts are being made against one of the following: the wrong site, wrong list, at the wrong time (ie the list doesn't exist yet or at at the time where the Alert is being set.)