Error: End tag for 'optgroup' which is not finished. You have probably failed to include a required child element. Hence the parent element is "not finished", not complete. I want to achieve something like this in select options. USA UK -- Afghanistan I want to put few important countries on top and then a non-selectable divider and then ordered list of remaining countries. I put this divider using empty 'optgroup'. While it works perfectly in all browser, I get validation error. What could be other approaches?