I’m not sure of the reason, but I couldn’t find anyone else posting about this so I figured I’d put it out there incase another puzzled developer goes looking.  In an application I’m working on (that happens to use Telerik radAjaxManager for this postback) I would consistently get this error, which as many will know is something you can get if you start adding controls to the tree in a page event that happens after Init, but I wasn’t adding any controls.  Turns out that this error completely goes away if I disable my break points.  Even if I’m still debugging, but my break points are disabled, I never see this error.

I don’t know what’s going on but maybe someone else will see this same post and know that they are not alone.