Hello !
I already tried, this does not solve the problem (deactivate everything, the website went down… the all Kleo theme is linked to those components).
I finally find what the problem was : my page was hosted at https://www.mywebsite.com and the link was trying to validate the subscription form to https://mywebsite.com. When the page was reloading, it kept the content (except the password, security purpose I think) but it was exactly the same page (nothing was sent to the new subscriber, nothing was sent to the database neither the admin).
By changing the all website to https://www.mywebsite.com/ this solved the problem 🙂
Thank you for yor time Danbp !
