How to fixed this error in Contact Form & multi step - wordpress

Question

I`m using Contact form Multi Step plugin in wordpress, i have 5 form and everytime I press the previous button it will not redirect to the previous form
Hi guys Everytime I press the previous button it has an error:
Error:
{"code":"rest_no_route","message":"No route was found matching the URL and
request method","data":{"status":404}}
Additional:
And Everytime i submit the thank you message appear

Answer 1

The answer below is an unofficial fix of a bug with Contact Form 7 Multi-Step Forms v2.1 on WordPress v4.7.5.
The plugin does not work properly anymore according to the author's update.
UPDATE: This plugin still works as expected for most people, but it does not for some.
To fix this, you will have to edit some codes of the plugin.
Update this function in wp-content/plugins/contact-form-7-multi-step-module/form-tags/module-back.php.
/**
* Handle the back form shortcode.
*/
function cf7msm_back_shortcode_handler( $tag ) {
if (!class_exists('WPCF7_Shortcode') || !function_exists('wpcf7_form_controls_class'))
return;
$tag = new WPCF7_Shortcode( $tag );
$class = wpcf7_form_controls_class( $tag->type );
$atts = array();
$atts['class'] = $tag->get_class_option( $class );
$atts['id'] = $tag->get_id_option();
$atts['tabindex'] = $tag->get_option( 'tabindex', 'int', true );
$value = isset( $tag->values[0] ) ? $tag->values[0] : '';
$previous_url = isset( $tag->values[1] ) ? $tag->values[1] : '.';
if ( empty( $value ) ) {
if ( $tag->type == 'previous') {
$value = __( 'Previous', 'contact-form-7-multi-step-module' );
}
else {
//using old version
$value = __( 'Back', 'contact-form-7-multi-step-module' );
}
}
$atts['type'] = 'button';
$atts['value'] = $value;
$atts['href'] = $previous_url;
$atts = wpcf7_format_atts( $atts );
$html = sprintf( '<input %1$s />', $atts );
return $html;
}
And update 1 line in wp-content/plugins/contact-form-7-multi-step-module/resources/cf7msm.js changing
window.location.href = val[step_field.val()];
to
window.location.href = $(this).attr('href');
Finally, you need to change how you insert [previous] tag in contact form. After making the changes above, the [previous] tag works like so.
[previous "Button Label" "URL of previous step"]