How do I enable a Let’s Encrypt SSL certificate with ISPConfig?

Procédure

An SSL certificate allows you to access your site with an address starting with https:// and encrypts exchanges between the site and its visitors.

ISPConfig can generate a free Let’s Encrypt certificate for a site already configured on your VPS. The certificate will then be renewed automatically, provided that the domain continues to point correctly to the server.

Before you begin

The site must already have been added in ISPConfig.

The domain name must also point to your VPS IP address. If you want to use the address with www, it must also point to the server.

Enable Let’s Encrypt in ISPConfig

1. Log in to your ISPConfig interface.
2. Open the Sites (1) menu.
   
3. In the Websites (2) section, click the relevant domain name (3).
4. In the site settings, check the following options:
   • SSL;
   • Let’s Encrypt SSL.
     
5. Check that the field linked to the automatic subdomain matches the address you want to use:
   • choose a configuration with www if your site must be accessible with and without www;
   • do not add www if this address is not configured in your DNS zone.
6. Click Save.

ISPConfig then starts creating the certificate. The operation may take a few minutes.

Check that the certificate works

Open your site in a new tab using an address starting with https://, for example:

https://your-domain.fr

If you have also configured the address with www, test it separately:

https://www.your-domain.fr

Installing the certificate makes HTTPS available, but it does not necessarily redirect visitors who are still using an address with http://.

To automatically force the use of HTTPS, you will need to set up a script (.htaccess) or a plugin (if using a CMS) to perform the automatic redirection.

Common issues

The Let’s Encrypt option becomes unchecked after saving

This usually means that ISPConfig was unable to generate the certificate.

Check the following elements:

• the domain does indeed point to the VPS IP address;
• DNS propagation is complete;
• the address with www also points to the VPS if it is enabled in ISPConfig;
• no old IPv6 record is directing the domain to another server.

After correcting the pointing, check SSL and Let’s Encrypt SSL again, then save.

The site works without www, but not with www

The www address probably does not point to your VPS or was not included in the site configuration.

Check the DNS record for www, then review the automatic subdomain setting in ISPConfig.

A certificate warning appears in the browser

Check that you are viewing exactly the domain name for which the certificate was created.

A certificate generated only for your-domain.fr does not necessarily cover www.your-domain.fr, and vice versa.

My site remains accessible over HTTP

This behavior is normal if no redirection has been configured. The certificate enables HTTPS, but does not automatically force its use.

Set up a permanent redirect from HTTP to HTTPS to send all visitors to the secure version of the site.

HTTPS works, but some resources are reported as insecure

Your site is probably still loading images, scripts, or style sheets with addresses starting with http://.

Replace these addresses with their https:// version or correct your application’s configuration.