Gets or sets a value that indicates whether postbacks from immediate child controls of an UpdatePanel control update the panel's content.
Assembly: System.Web.Extensions (in System.Web.Extensions.dll)
Set the property to true if you want postbacks from immediate child controls of the UpdatePanel control to cause an update of the panel's content. Child controls of nested UpdatePanel controls will not cause an update of the parent UpdatePanel control's content unless you call the Update method explicitly or you define the child controls as triggers.
When the UpdateMode property is set to Always and the property is set to false, an InvalidOperationException exception is thrown during the OnPreRender method. This combination of properties is not allowed for the UpdatePanel control.
A scenario where you might set to false is when you have two UpdatePanel controls and you want a postback from the first panel to update the content of the second panel but not update its own content. For example, the first panel might be a list of products to buy and the second panel might be a shopping cart.