Note:
That property has effect only when EnableLoadOnDemand is true.
If it is enabled, then all once loaded templates are reloaded on all full postbacks.
While asynchronous postbacks all once loaded templates in UpdatePanels are reloaded regardless of that property, otherwise, server raises exception due to failed EventValidation.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2