: str_replace(): Passing null to parameter #2 ($replace) of type array|string is deprecated in
add_action( 'wpcf7_init', 'wpcf7_add_form_tag_hidden', 10, 0 );
function wpcf7_add_form_tag_hidden() {
wpcf7_add_form_tag( 'hidden',
'wpcf7_hidden_form_tag_handler',
'display-hidden' => true,
function wpcf7_hidden_form_tag_handler( $tag ) {
if ( empty( $tag->name ) ) {
$class = wpcf7_form_controls_class( $tag->type );
$atts['class'] = $tag->get_class_option( $class );
$atts['id'] = $tag->get_id_option();
$value = (string) reset( $tag->values );
$value = $tag->get_default_option( $value );
$atts['type'] = 'hidden';
$atts['name'] = $tag->name;
$atts = wpcf7_format_atts( $atts );
$html = sprintf( '<input %s />', $atts );