This is an intermittent exception that occurs intermittently in Umbraco 3.0.4 running in IIS 6
When an umbraco user logs in and selects a document to edit occasionally they get this...
[NullReferenceException: Object reference not set to an instance of an object.]
umbraco.controls.ContentControl.addControlNew(Property p, TabPage tp, String Caption) +242
umbraco.controls.ContentControl..ctor(Content c, publishModes CanPublish, String Id) +832
umbraco.cms.presentation.editContent.OnInit(EventArgs e) +442
System.Web.UI.Control.InitRecursive(Control namingContainer) +321
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +692
Once the error has occurred, it will persist for every user logged in to umbraco until we restart the application pool (it's running in it's own) so it must be some global state being corrupted, but it can run for days without a problem, but then can require a number of restarts in a day.
If I debug in to the app it always works and if I run debugvw on the server in a broken state it doesn't give me any more information. (other than the HTTP referer)
There are a number of dead end posts all over the web like this one but none seem to provide any concrete ways to reproduce.
I know it's a long shot, but has anyone here experienced and resolved this issue?
Upgrading is unfortunately not an option at the moment.
Thanks everyone.