In the Admin, if I go into an existing product and add a second category and hit save, the following error appears in the TreeView node of the new category:
Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
Is this a known error and is there a fix to it? It's true that EnableEventValidation is set to true, but for security reasons that setting should be preserved if possible, and that it how Kartris came.