You can set up Web.config to allow uploading of large files by ASP .NET applications.

By default, Machine.config is configured to accept HTTP Requests upto 4096 KB (4 MB) and it is reflected in all your ASP.NET applications. You can change the Machine.config file directly, or you can change only the Web.config file of the application(s) you want to.

Open your Web.config file, and just below the <system.web> tag, add the following tag:

<httpRuntime
executionTimeout="120"
maxRequestLength="4096"
useFullyQualifiedRedirectUrl="false"
minFreeThreads="8"
minLocalRequestFreeThreads="4"
appRequestQueueLimit="100"
enableVersionHeader="true"
/>

Now, just take a look at the maxRequestLength="4096" attribute of the <httpRuntime> tag. As you may have realized, all you need to do is change the value to some other value of your choice (8192 for 8 Mb, 16384 for 16 Mb, 65536 for 64 Mb, and so on...).