Could not find UpdatePanel with ID 'xxx'. If it is being updated dynamically then it must be inside another UpdatePanel

Question

I have a page with Ajax Tab controls, within one of the tabs is a webcontrol that as a Telerik RadGrid, with Edit forms pointing to another web control. That edit form also cont

Answer 1

This issue occurs in Telerik RadAjaxManager when you adds invisible controls to it.

So in case of your in need to show/hide AJAX controls, it is recommended to add AJAX settings grammatically from you code behind (based on control visibility state) instead of ASPX code.

For more information: Please check this answer on the Telerik forums.