The default size limitation in ASP.NET is 4MB. To overcome that size, you will need to add the following under System.Web section of either the Machine.Config file (to make it system wide), or Web.Config file (to make it application wide) :

executionTimeout="90"

maxRequestLength="4096"

useFullyQualifiedRedirectUrl="false"

minFreeThreads="8"

minLocalRequestFreeThreads="4"

appRequestQueueLimit="100" />

Please note that the highlighted ones are must, in order to increase the upload file size limitation.The values in the example are default value. You should make it larger.http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnaspp/html/aspnet-fileupload.asp