Problems with th ssl certificate

I have two domains in my account. One of them is being used in the public profile and was connected directly through the account settings page. This domain has been used this way for a long time, and after my Readymag subscription expired and I later renewed it, the website still works, but the www version shows an SSL error.

The other domain is used for a specific project and was mapped within the Domain Settings on the project page itself. This site does not open at all, neither with www nor without www. All the DNS records are correct, especially since I have been using this Readymag feature for a long time and it has always worked without any problems.

I’m not sure how to solve this issue. Could someone help me?