asp.net - OnClick Event for Button in GridView is not working -

here datagridview

<asp:gridview id="gvpredstave" runat="server" cssclass="gridview"          alternatingrowstyle-cssclass="even" autogeneratecolumns="true">         <columns>             <asp:templatefield>                 <itemtemplate>                     <asp:button id="btnrezervisi" runat="server" text="rezervisi" onclick="button1_click" />                 </itemtemplate>             </asp:templatefield>         </columns>     </asp:gridview> 

this code click on button in gridview

protected void button1_click(object sender, eventargs e)     {         response.redirect("aktivnerezervacije.aspx?korisnicko_ime=" + korisnicko_ime);         conn.close();     } 

when click on button got error in browser:

invalid postback or callback argument.  event validation enabled using <pages enableeventvalidation="true"/> in configuration or <%@ page enableeventvalidation="true" %> in page.  security purposes, feature verifies arguments postback or callback events originate server control rendered them.  if data valid , expected, use clientscriptmanager.registerforeventvalidation method in order register postback or callback data validation. 

does know reason why happening. tried enableeventvalidation="false" doesn't work.

i recreated error using gridview , binding it. answer lies on page_load event. if have this:

protected void page_load(object sender, eventargs e) {     bindgridview(); //code bind gridview } 

you exception. change to:

protected void page_load(object sender, eventargs e) {     if (!ispostback)     {         bindgridview();     } } 

and should not error anymore.