Extender controls may not be registered before PreRender

My solutions have been working fine, but I guess I updated or something and now when I click a handler, I get this message:

Extender controls may not be registered before PreRender

I've been reading everything from re-install ajax to add base.onprerender(), but nothing is working.

[InvalidOperationException: Extender controls may not be registered before PreRender.]
   System.Web.UI.ScriptControlManager.RegisterExtenderControl(TExtenderControl extenderControl, Control targetControl) +404173
   System.Web.UI.ScriptManager.RegisterExtenderControl(TExtenderControl extenderControl, Control targetControl) +95
   System.Web.UI.ExtenderControl.RegisterWithScriptManager() +155
   System.Web.UI.ExtenderControl.OnPreRender(EventArgs e) +19
   AjaxControlToolkit.ExtenderControlBase.OnPreRender(EventArgs e) +58
   AjaxControlToolkit.HoverMenuExtender.OnPreRender(EventArgs e) +37
   System.Web.UI.Control.PreRenderRecursiveInternal() +83
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Control.PreRenderRecursiveInternal() +155
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +974

I'm not really understanding because everything worked before.  I reversed all my changes and I still get the same error on click.

I also want to add that I don't see the ajaxToolkitScriptManager in the toolbox ...

Extender controls may not be registered before PreRender