Problème Facebook

Hello, I entered the Messenger PIN code because I was asked for it, and when I go to a friend's profile, I see this message: "These messages were sent before end-to-end encryption of this conversation. You cannot reply, react, or forward." with a banner that says "continue." The problem is that when I click on "continue," nothing happens, and therefore I can't send messages to this friend; even when I go to her profile and click on "send a message"..... (For your information, this only happens with this person.) How can I communicate with her? I've tried on my mobile and on my computer, but nothing works. Thank you for your help.