I was able to get past the HTTP 500 error by adding my handlers to the <system.webServer><handlers> section in my web.config like this:
<add name="Handler_ashx" verb="*" preCondition="integratedMode" path="Handler.ashx" type="Telerik.Web.UI.WebResource" />
<add name="StreamImage_ashx" verb="*" preCondition="integratedMode" path="StreamImage.ashx" type="Telerik.Web.UI.WebResource" />
Possibly this is obvious to everyone else but it certainly wasn't to me!
In any case, while the upload portion of the demo appears to work now, it will not hit any breakpoints in handler.ashx.vb -- I need to intercept flow within the handler to start my own customization work. Any idea what I'm doing wrong?
thx -- john