I have been receiving this error:
" Invalid postback or callback argument. Event validation is enabled
using 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. "
This has only been experienced by users who have been using the website whilst the same page has been updated. It has been reported occasionally during busy times too. The problem arises from a asp.net 2.0 drop-down control that is in an Ajax Update Panel (i.e., when a user selects an item from it). But, it only occurs in the scenario I have described.
This occurs usually from users using Firefox, though it has occurred sometimes with IE7 users. However, I can only recreate the problem in Firefox.
I've tried a number of possible solutions using the ClientScriptManager.RegisterForEventValidation, but none have solved this problem. Changing <%@ Page EnableEventValidation = "false" %> has temporarily solved the problem, but I don't really want this solution long term.
The project is an ASP.Net 2.0 AJAX enabled website. It uses masterpages.
Any help on this appreciated.
Thanks - Darren