<httpRuntime maxRequestLength="2097151" waitChangeNotification="1" maxWaitChangeNotification="3600" />
Change it to:
<httpRuntime requestValidationMode="2.0" maxRequestLength="2097151" waitChangeNotification="1" maxWaitChangeNotification="3600" />
Let me know if it works for you..!!
Request Validation Mode property gets or sets a version number that indicates which ASP.NET version-specific approach to validation will be used.
Let me know if it works for you..!!