I am not sure how this problem could be related to RadEditor? Note that it is not possible to configure the browser's settings of the client computers from the web.config file, because this will be a security problem. This setting is most likely disabled by the administrator of the client machine and it is not possible to be enabled from the server (from the web.config).
Are you able to reproduce the same problem with the regular ASP Upload control
<asp:FileUpload ID="FileUpload1" runat="server" /> ?
My suggestion is to search in Google, MSDN for solution.
All the best,
the Telerik team
Thank you for being the most amazing .NET community! Your unfailing support is what helps us charge forward!
We'd appreciate your vote for Telerik in this year's DevProConnections Awards. We are competing in mind-blowing 20 categories and every vote counts! VOTE for Telerik NOW >>