Just add this line in your web.config file.
<system.web>
<httpRuntime targetFramework=”4.5.2″ maxRequestLength=”1048576″ />
</system.web>
<system.webServer>
<security>
<requestFiltering>
<requestLimits maxAllowedContentLength=”1073741824″ />
</requestFiltering>
</security>
</system.webServer>