If you see the message:
Custom SSL certificates are no longer supported for free subdomains. All free subdomains have SSL by default.
That is because custom SSL certificates are no longer supported for free subdomains. And you don’t need them anymore either, because all free subdomains have SSL by default.
Please see the announcement of these changes on our forum for more information about this:
And next time, if you see an error message, please read the error message and try to understand what it means. After all, the purpose of error message is to tell you what is wrong. Error messages are not intended to provide unintelligible gibberish only the most technical nerds can make sense of, and you should never try to understand.