Page not found error when uploading big size files in ASP .NET

Objective: Solve the Page Not Found issue when try to uploading Big size files.
in ASP.NET


Issue: Wheneever we try to upload an big size file (more than 5 MB) immediately the
page expires and it say page not pound in ASP.NET.


Solution: To solve this issues we have to increase the execution time and max requestlength
in httpruntime tag in Web.config.In the below sample i have increased the both.

<httpRuntime maxRequestLength="400000" useFullyQualifiedRedirectUrl="true" executionTimeout="180"/>

hi,
By default, ASP.NET permits only files that are 4,096 kilobytes (KB) (or 4 megabytes [MB]) or less to be uploaded to the Web server. To upload larger files, you must change the maxRequestLength parameter of the <httpRuntime> section in the Web.config file.

Note When the maxRequestLength attribute is set in the Machine.config file and then a request is posted (for example, a file upload) that exceeds the value of maxRequestLength, a custom error page cannot be displayed. Instead, Microsoft Internet Explorer will display a "Cannot find server or DNS" error message.

If you want to change this setting for all of the computer and not just this ASP.NET application, you must modify the Machine.config file.

By default, the <httpRuntime> element is set to the following parameters in the Machine.config file:

<httpRuntime
executionTimeout="90"
maxRequestLength="4096"
useFullyQualifiedRedirectUrl="false"
minFreeThreads="8"
minLocalRequestFreeThreads="4"
appRequestQueueLimit="100"
/>


The Machine.config file is located in the \System Root\Microsoft.NET\Framework\Version Number\Config folder.

Try this, u can get more idea if u visit this url
How to upload a file to a Web server in ASP.NET by using Visual Basic .NET

Regards
Manivannan.s