How to install SSL certificate for domain alias in Plesk?
A separate certificate only for the domain alias cannot be created or uploaded. Instead, create a new Let's Encrypt certificate for the main domain and specify the alias to secure:
II. Create a new certificate:
- Go to Extensions > My Extensions tab > SSLIt! and click Install button in Recommended extensions next to Let's Encrypt icon.
- Go to Websites & Domains > SSL/TLS Certificates and click Get Certificates button. Scroll down to "More options" and click Install button next to "Install a free basic certificate provided by Let's Encrypt"
- Specify email address of domain owner.
- Specify if you want to include an alternative domain name for the domain and each selected alias, for example:
www.example.comfor example.com. It is recommended to select this checkbox.
- Specify if you want to include webmail, for example:
webmail.example.com. It is recommended to select this checkbox.
- Select the domain alias to secure and click Install
III. Secure the main domain with it's aliases:
- Go to Websites & Domains and click Hosting Settings.
- Select the SSL/TLS support checkbox.
- Select the newly issued Let's Encrypt certificate from the Certificate menu, and click OK.
To secure domain alias with a paid certificate, contact a certificate provider to add the alias name to the certificate as the subject alternative name (SAN). Then, secure the main domain with this certificate as described here.