Issue How to secure domain alias with Lets Encript

[VW Nut]

I have newdomain.com with a new website.
I have set olddomain.com as an alias of newdomain.com
But, browser wont go there, saying cert is only valid for newdomain not olddomain.
Can't seem to fix - any guidance?

 

[Bitpalast]

In the new Onyx versions when you create a Let's Encrypt certificate for the main domain, it offers you selection boxes where you can pick the aliases that you want to use an SSL certificate for, too. Simply click the Let's Encrypt icon, check the addtional options for the certificate and select your the alias, then renew (or setup) the certificate.