C # - Problem with RenderControl, 'RegisterForEventValidation can only be called during Render ()'

Question

I need to get the Html of GridView and send an email.

My GridView Project is mentioned below

 <div id="DivEmail" class="clear"> <asp:Repeater ID="rpt1" runat="server" OnItemDataBound="rpt1_ItemDataBound"> <ItemTemplate> <asp:HiddenField ID="TypeID" runat="server" Value='<%# Eval("TypeID") %>' /> <div id='Handle<%# Eval("TypeName")%>' class="ulheader" > <asp:Label ID="lblType" runat="server" Text='<%# Eval("TypeName")%>' ></asp:Label> </div> <div id="Reuslt<%# Eval("TypeName")%>"> <asp:GridView ID="grvReport" runat="server" Width="100%" BorderColor="#e4e4e4" border="0" Style="border-collapse: collapse;" ShowHeader="true" CellPadding="5" CellSpacing="0" AutoGenerateColumns="false" EmptyDataText="No Results Found" AllowPaging="false" AllowSorting="false" CssClass="grid grid-iq" BackColor="#FFFFFF"> <Columns> <asp:TemplateField HeaderText="Image"> <ItemTemplate> <asp:Image ID="thumb" Width="100px" Height="100px" runat="server" ImageUrl='<%# Eval("ImageUrl") %>' ImageAlign="Middle" /> </ItemTemplate> ItemStyle CssClass="center" Height="20px" /> <HeaderStyle CssClass="grid-th center" Width="100px" VerticalAlign="Top" /> </asp:TemplateField> <asp:BoundField DataField="Title" HeaderText="Title"> <HeaderStyle Height="20px" Width="20%" CssClass="grid-th-left" VerticalAlign="Top" /> <ItemStyle CssClass="left"></ItemStyle> </asp:BoundField> <asp:BoundField DataField="Description" HeaderText="Description"> <HeaderStyle Height="20px" Width="28%" CssClass="grid-th-left" VerticalAlign="Top" /> <ItemStyle CssClass="left"></ItemStyle> </asp:BoundField> <asp:TemplateField ShowHeader="false" HeaderText="View"> <ItemTemplate> <asp:LinkButton ID="lbtnLink" runat="server" CommandArgument='<%# Bind("ID") %>' OnCommand="lbtnView_OnCommand" Text="View"></asp:LinkButton> </ItemTemplate> <ItemStyle CssClass="center" Height="20px" /> <HeaderStyle CssClass="grid-th center" Width="9%" VerticalAlign="Top" /> </asp:TemplateField> </Columns> <HeaderStyle CssClass="grid-th" Height="10px" HorizontalAlign="Center" VerticalAlign="Top"></HeaderStyle> </asp:GridView> </div> </ItemTemplate> </asp:Repeater> </div> 

To capture the Html server management I use below code

 protected void btnOK_Click(object sender, EventArgs e) { var sb = new StringBuilder(); DivEmail.RenderControl(new HtmlTextWriter(new StringWriter(sb))); EmailContent += sb.ToString(); } public override void VerifyRenderingInServerForm(Control control) { /* Confirms that an HtmlForm control is rendered for the specified ASP.NET server control at run time. */ } 

So I get an exception

 RegisterForEventValidation can only be called during Render() 

I worked a little on the problem, the results say that set EnableEventValidation="false" to @page directive . but I can not use this solution.

Can someone help me solve this?