This article lists the most common issues related to RadImageEditor:
The most likely reason for this behavior is that the HttpHandler is not present in the web.config. These three operations are not performed on the client and thus require that the RadImageEditor can properly communicate with the server.
The easiest approach to enable the Telerik HttpHandler is to go to the design view in VS, show the Smart Tag of the RadImageEditor and select the Enable RadImageEditor HttpHandler option. For more information, see the Smart Tag article.
You can also manually add the needed handlers under system.web -> httpHandlers for IIS versions prior to 7.0. For example:
<system.web> . . . . <httpHandlers> <add path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" verb="*" validate="false" /> </httpHandlers> </system.web>
and under system.webServer -> handlers for ISS 7.0 and later. For example:
<system.webServer> <modules runAllManagedModulesForAllRequests="true" /> <validation validateIntegratedModeConfiguration="false" /> <handlers> <add name="Telerik_Web_UI_WebResource_axd" verb="*" preCondition="integratedMode" path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" /> </handlers> </system.webServer>
When RadCompression is enabled and you are using .NET 4.0, event handlers might not be raised in a default document in IIS 7 or IIS 7.5 Integrated Mode, which could break the normal work of RadImageEditor.
This problem is caused by a breaking change in .NET 4.0 described here. To work around it, you can set preCondition="managedHandler" for the RadCompression module. You may also need to remove the runAllManagedModulesForAllRequests setting from your web.config if you have it (or set it to false).
By design RadImageEditor can work only with virtual paths pointing to images placed inside its application root directory. Using images from external URLs (http://host/image.jpg) or physical location (C:/images/image.jpg) is not supported out-of-the-box. Such configuration may lead to not rendered or not editable image (so the image operations will not work properly on it).
SecurityError: The operation is insecure.
There are several possible ways to resolve the problem: