Firefox

[Jeanjean]

The following could be the possible causes:
1) Messing with the browser settings (certificate settings in particular)
2) Add-ons blocking the pages

You can reset your browser settings (Refresh Firefox) and remove all the add-ons and try it again.
https://support.mozilla.org/en-US/kb/res...x-problems

I knew that.
However, since I had not modified Firefox (no new addon, not yet installed the latest version) I was wondering why all of a sudden I could no longer log in.
The problem must have existed for some time without my realizing it. I use the 2 sites mentioned only exceptionally.

Anyway, I give the solution higher and thank you for your intervention.