EXCEL Import problems

Hi, please, when trying to export my form to EXCEL, the following error is generated.

Can not access this site.
error http://xxxx/wp-admin/admin-ajax.php?action=cfdb-export&form=prueba&enc=xlsx&regionaldelimiter=true
It does not work temporarily or has been permanently moved to a new web address.
ERR_INVALID_RESPONSE

Thank