Maximum request length exceeded

Maximum request length exceeded.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.            
Exception Details: System.Web.HttpException: Maximum request length exceeded. 

Add this entry in <system.web> 

<httpRuntime maxRequestLength="524288" executionTimeout="120000" /> 

And this in <system.webserver> 

<security>
     <requestFiltering>
          <requestLimits maxAllowedContentLength="524288000"
     </requestFiltering>
</security> 

This will increase the max Request lenght to 500MB. Pay attention to the size format. In the first case it's expressed in KBytes, instead in the second one it's in Bytes.
You'll need both to manage it to work