XF 2.0 data-xf-click=overlay does no longer work



I have currently an issue with the overlay functionalities on a forum.
Each time I click on a link that specifies data-xf-click=overlay, nothing happens. However it works fine when follow the URL directly with the URL.
For example Sugn up / Login does not work when I click on the button (the 3 bars display for a few second then disappeared and nothing changed) but if I follow directly the URL /register/ it works.
Forum is: https://www.les-cabanes.com/forum-cabane/

Is it a lib issue ? something preventing data-xf-click ? Any help would be greatly appreciated.
Many thanks in advance.

Chris D

XenForo developer
Staff member
This isn't going to be an issue with the software itself. It seems as though the XML HTTP request is starting and then it gets cancelled. The browser console reports ERR_SPDY_PROTOCOL_ERROR which sounds like an issue at the web server level.