How to Fix Plesk Update Errors Caused by IPv6 Connectivity Issues

System administrators often encounter unexpected issues while performing routine updates. One such common problem arises when Plesk attempts to verify connectivity during an upgrade, especially on servers where IPv6 is enabled but not fully configured.

Recently, while updating Plesk, I ran into the following error:

Plesk was unable to connect to required ports over IPv6, causing the pre-upgrade checker to fail. The root cause was simple: IPv6 was enabled on the server, but the network or firewall did not properly support IPv6 routing, leading to timeouts on ports 8880 and 8443.

Why This Error Occurs

Plesk attempts to verify its accessibility over all configured IP addresses—both IPv4 and IPv6.
If the server has IPv6 enabled but:

• The hosting provider does not route IPv6 properly
• Firewall rules do not allow traffic on IPv6
• The IPv6 stack is misconfigured

Then Plesk cannot reach itself, resulting in connectivity and upgrade warnings.

Solution: Disable IPv6 on the Server and in Plesk

1. Remove IPv6 Assignments From Hosted Domains

Before disabling IPv6 globally, ensure no domains rely on it.

1. Go to: Tools & Settings → IP Addresses
2. Select the IPv6 address
3. Check the Sites column
   
4. For each domain using IPv6:
   • Go to Domains → <domain> → Web Hosting Access
   • Set IPv6 address to None

This prevents Plesk from breaking domain configurations after IPv6 removal.

2. Disable IPv6 at OS Level

SSH into the server and add the following lines to /etc/sysctl.conf:

net.ipv6.conf.all.disable_ipv6=1
net.ipv6.conf.default.disable_ipv6=1

Apply the configuration:

sysctl -p

This completely disables the IPv6 networking stack on the operating system.

3. Remove IPv6 From Plesk

Finally, tell Plesk to forget IPv6 addresses.

You can either remove them manually or use the auto-detection feature:

Tools & Settings → IP Addresses → Reread IPs

This forces Plesk to rescan the interface list and remove IPv6 entries that no longer exist.

4. Proceed With the Plesk Update

After completing the above steps, simply continue running the Plesk update. With IPv6 fully disabled and removed, the update process will proceed smoothly without any port connectivity errors.

Conclusion

This solution is helpful for any server where:

• IPv6 is enabled by default by the hosting provider
• IPv6 is not actively used
• Plesk updates fail with port connectivity warnings

If your system doesn’t rely on IPv6, disabling it can reduce complexity and prevent similar issues during future updates.

If you’re still facing IPv6 Connectivity Issues Causing Plesk Update Error, our experts are here to help. With reliable Plesk Server Management Services and Linux Server Support Services, we ensure smooth updates, stable networking, and hassle-free server operations. Contact us today for professional assistance and peace of mind.