Commented Issue: System.NullReferenceException: Object reference not set to an instance of an object. [26752]

From time to time, my clients gets this error.

System.NullReferenceException: Object reference not set to an instance of an object.
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at AjaxControlToolkit.ToolkitScriptManager.GetScriptCombineAttributes(Assembly assembly)
at AjaxControlToolkit.ToolkitScriptManager.IsScriptCombinable(ScriptEntry scriptEntry)
at AjaxControlToolkit.ToolkitScriptManager.OnResolveScriptReference(ScriptReferenceEventArgs e)
at System.Web.UI.ScriptManager.RegisterScripts()
at System.Web.UI.ScriptManager.OnPagePreRenderComplete(Object sender, EventArgs e)
at System.Web.UI.Page.OnPreRenderComplete(EventArgs e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
Comments: AjaxControlToolkit is antiquated technology. It is unlikely that MS will be fixing it. The right thing to do is to think about the future and begin planning for an upgrade to MVC. There was a fork a ways back that did help us for a while at least while we transitioned away from web forms over to MVC... We still have some older pages in our main CMS that use it and with the fork at the url below, we do not have this issue at all. http://ajaxcontroltoolkit.codeplex.com/SourceControl/network/Forks/etolmachev/ToolkitScriptManager26752 If the above does not help you then I would say the urgency on that MVC upgrade is a lot higher for you... That or go in and make your own fix/fork of the toolkit and post it here for others to use. :)