Export to Excel not working

Hello. When I try to export the form submissions into Excel, it shows me the following error. Any help?

This site can’t be reached

The web page at http://domain.com/wp-admin/admin-ajax.php?action=cfdb-export&form=MyFirstForm&enc=xlsx&regionaldelimiter=true might be temporarily down or it may have moved permanently to a new web address.
ERR_INVALID_RESPONSE

Thank you!