for asp.net, there are 2 spaces to set the maximun upload size.

1. in web.config, like this

<httpRuntime executionTimeout="6000" maxRequestLength="150000" />

2. in IIS=>Request Filtering:

if your upload file is exceed the max lengh, you will get error like

404 – File or directory not found.

The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable.