Error when exporting GridView to Excel

Fix for error :" Control 'ctl00_ContentPlaceHolder1_Gridview1' of type 'GridView' must be placed inside a form tag with runat=server"

Fix: Add the following code in cs file.

public override void VerifyRenderingInServerForm(Control control)
{
// Confirms that an HtmlForm control is rendered for the
//specified ASP.NET server control at run time.

}