UserControl does not have public property named ContentTemplate

Question

This question has been asked a few dozen times before; but has never been solved.

i have an UpdatePanel

Answer 1

You should solve this per design.

Put your update panel on a page and make the user control without an update panel.

reason: the update panel is intended to autogenerate clientside scripting for asyncronous postback as you surely know. The user control is a building block with a self contained functionality encapsulating complexity which should be placeable anywhere without requirements to the context and in this case at least you would need a scriptmanager on the page which instantiates the control.