Can't install SSL certificate

Please read the text on the banner pinned at the top of the forum:

Since the servers are in the process of being upgraded, issues are expected to appear. For some, their websites seem to be inaccessible. In your case, it seems that your SSL configuration isn’t being reflected on your website. This is likely related to the migration; it should be fixed once it’s complete.

You can track the process of the migration here: