Page.AsyncMode Property
Sets a value indicating whether the page is processed synchronously or asynchronously.
Assembly: System.Web (in System.Web.dll)
The AsyncMode property is set by the Page parser when code for the page is generated. Use the Async attribute in @ Page directive to set this value.
Asynchronous pages do not work when the AspCompat attribute is set to true or the Transaction attribute is set to a value other than Disabled in the @ Page directive.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.