VIT Blog

if your webpage submits a file for uploading, and the page returns an error on larger file sizes, then look for 2 attributes to modify in your web.config .

open you web.config file and seach for the following line:

<httpRuntime executionTimeout="480" maxRequestLength="7168"/>

executionTimeout is the time limit before the request timesout and you get an error, this figure is represented in seconds (480 = 8 minutes)
maxRequestLength is the file size represented in KB (1024 = 1MB, 7168 – 7MB)

for detailed info, go to: http://msdn.microsoft.com/en-us/library/e1f13641(VS.71).aspx