__EVENTTARGET empty?

There are different mechanism for different controls for postback.
Above one will work for CheckBoxes, DropDownLists, LinkButtons, etc, this does not work for Button controls.


For button controls, If you take a look at how the server controls render as HTML, you'll see that the buttons do not call the __doPostBack Javascript function so the __EVENTTARGET is never set. Instead, the Buttons render as simple input type=“submit” tags.

Since the button (or input) is what causes the form to submit, it is added to the items in the Form collection, along with all the other values from the submitted form.

So you can find the postback control by the following method

public static Control GetPostBackControl(Page page)
{
    Control control = null;
    string ctrlname = page.Request.Params.Get("__EVENTTARGET");
    if (ctrlname != null && ctrlname != string.Empty)
    {
        control = page.FindControl(ctrlname);
    }
    else
    {
        foreach (string ctl in page.Request.Form)
        {
            Control mycontrol = page.FindControl(ctl);
            if (c is System.Web.UI.WebControls.Button)
            {
                control =mycontrol ;
                break;
            }
        }
    }
    return control;
}

Hope this will solve your problem.

Just add UseSubmitBehavior="False" to your button. This worked for me
c# - __EVENTTARGET is empty on postback of button click - Stack Overflow[^]

Thank you. Understand your explanation but don't understand the pasted solution. The For loop iterates over all the controls on the page and checks if the control is a button. What happens if there are more than one button?