A website is not accessible over IPv6: ERR_CERT_COMMON_NAME_INVALID

Symptoms

• A website is not accessible with the following error message (or similar) appearing in a web browser:

  NET::ERR_CERT_COMMON_NAME_INVALID

• Globally, the website resolves to an IPv4 address successfully:

  # nslookup example.com 8.8.8.8
  Server: 8.8.8.8
  Address: 8.8.8.8#53

  Non-authoritative answer:
  Name: example.com
  Address: 203.0.113.2

• When opening the website in a browser Web Console (F12), the IPv6 address of the server appears under the Remote IP table in the Network tab.

• On the registrar side, the website is configured to use both IPv4 and IPv6.

Cause

IPv6 is not set for the domain on the side Plesk and therefore the website can be resolved only via the IPv4 address of the server.

Resolution

1. Log into Plesk

2. Go to Domains > example.com > Hosting & DNS > Hosting

3. Scroll down to the IP addresses section and make sure the correct IPv6 address is selected for this website

4. Press on Save

Additional information

How to enable IPv6 addresses on a Plesk server?

IP Addresses Management | Plesk Obsidian documentation

How to add IPv6 address for all subscriptions that have specific IPv4 in Plesk?