Full Error :
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.
I have used the CascadingDropDown Control for 2 combo boxes I have within an Update Panel.
The 2 Combo boxes are in a user control which is embeded on an aspx page which inherits from a master page.
The page loads fine and on clicking a button to cause a postback all works fine. HOWEVER, selecting a value from Combo1 udpates Combo2 with values via the CascadingDropDown control. This works fine. Now if you click the save button you receive the "Invalid postback or callback argument" error.
Is there a way around this. On the ASP>NET forum, Scott Gu states that the CascadingDropDown extended handles all of this for you (http://forums.asp.net/4/1419678/ShowThread.aspx
- near bottom of page 4) however this does not appear to be the case.
Any suggestions of fixes to this?