This member overrides Control.OnInit(EventArgs), and more complete documentation might be available in that topic.
Assembly: System.Web (in System.Web.dll)
Web server controls should perform any initialization steps that are required to create and set up an instance. You cannot use view state information within this event; it is not populated yet. You should not access another Web server control during the method, regardless of whether it is a child or parent to the ChangePassword control. Other Web server controls are not certain to be created and ready for access.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.