I have installed a fresh instal of DNN 7.2.2 and tested the image upload from the file manager screen it works with no errors,
I then instal a fresh copy of smithcart 6.0 and tested the file opload and when i click the button I get a timer circle spinning for hours but nothing else happens. I do not have this error with the previous version of smithcart. 

Hi Benny,

Try adding the following to the section of your web.config file:

<add name="Telerik_Web_UI_DialogHandler_aspx" verb="*" preCondition="integratedMode" path="Telerik.Web.UI.DialogHandler.aspx" type="Telerik.Web.UI.DialogHandler" />

Please post back with an update.

Thanks!