In the webconfig, add following two:
<configuration>
<system.web>
<!--unit in kb-->
<!-- default 4096 -> 4MB -->
<httpRuntime maxRequestLength="50000" /> <!--so this will be 50MB -->
</system.web>
</configuration>
This is setting the iis
<system.webServer>
<security>
<requestFiltering>
<!-- unit in byte-->
<!-- default 30000000, which is approximately 28.6MB -->
<requestLimits maxAllowedContentLength="52428800" /> <!--50MB-->
</requestFiltering>
</security>
</system.webServer>