What is this Issue...?

> This error happens in the following situation.
> When you modify Asp.Net controls from client side after page is completely loaded.
> Then if you do a postback, you will get this error.
> This is because, when page load happens, Asp.Net controls will get registered.
> And the controls get validated when postback happens.
> During postback validation, if any mismath happens, you will get this error.
> This is a type of Asp.Net security that prevents any unauthorized postback requests.

Solution 1 - Disable EventValidation.

> On your Aspx page, set EnableEventValidation as false.
> We strongly recommend not to disable EventValidation.

Solution 2 - Use Update Panel

> The best option is to use update panel for updating Asp.Net controls.
> This would definitely allow you to update only a particular control.
> As shown in the figure, we can use update panel in Aspx page and code behind.

Solution 3 - Use Server Side DataBind For Controls

> If nothing works for you, then go with normal Server side postback for binding controls.
> By this way you will definitely get validated on each callback.
> This will definitely resolve your issue.

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