In my webform I am using Jquery and Javascript for popup window and clientside validation.
In the popup window I add the combobox item using javascript. It's all works well.
But When I save the form
The following error occurs
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.
If I remove the update panel, when I select newly additem in the combobox, the above error is occured
Why? help me....