Problem after CF7 3.9 update

Hi,

I’m using forms 3rd party plugin with CF7 for CRM lead export.

since I’ve made the update of CF7 to version 3.9 today, the form can’t submit (the little wheel keeps turning on, without returning any success message).
Firebug console indicates me this:

Warning: array_merge() [function.array-merge]: Argument #2 is not an array in /home/mysite/www/wp-content/plugins/forms-3rdparty-integration/plugins/contactform7.php on line 154
{"mailSent":true,"into":"#wpcf7-f1314-o1","captcha":null,"message":"Your message has been sent \u00e9t\u00e9 envoy\u00e9. Merci.","onSentOk":["location = '\/';"]}

It clearly appears 3rd party plugin is blocking something but what?
Does any of you know what can I do please?

Thanks for the help

https://wordpress.org/plugins/contact-form-7/