Hello Benjamin,
After installing the new version of the Telerik UI for ASP.NET AJAX you should have a folder in the Program Files/Telerik path corresponding to the the version. There you can fond all the resources you need. You can also find them in the manual installation package under the EditorDialogs folder.
If, however, you do not have any customization regarding the dialogs, I suggest you to rather use the built-in ones. If you consider doing that, remove the ExternalDialogsPath property and delete the folder that holds the external user control files.
Regards,Ianko
Telerik by Progress
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