Thanks very much for your help. I am using Radius and I noticed that the problem wasn’t there until I installed BuddyPress.
I searched my code and found the unsecure content refers to “_wp_http_referer”. I think that instead of correcting manually this big number of insecure items, I am going to use a plugin. I have found one “SSL Insecure Content Fixer”, I am going to test and will give a feedback to the community.
Thanks for your reply. In fact when I activate BuddyPress I get a notification that the SSL communication is validated on my site but that it has started including other non-secure resources that could be leveraged by third-parties to make my site misfunction.
I do not neither know nor understand the origin of this third-party code. Is it from the BuddyPress plugin itself? What is it about then?
Thanks to @all the community and to you @r-a-y and @imathi for your help