Disclaimer

Known affected versions were inferred from fixed-version data and were not explicitly confirmed by the vendor: 11.1.12, 11.2.10-h13, 12.1.3-h3

The earliest recollection of this bug is traced back to PAN-OS 11.1.13 - October 14, 2026. This bug is fixed in PAN-OS versions 11.1.13, 11.2.11, 11.2.10, 12.1.4. ( VM-Series firewalls on Microsoft Azure environments in HA configurations only ) Fixed an issue where, when an interface was configured with IPv6, the firewall displayed the message Unknown error during validation after the client secret expired, which caused DNS resolution to fail when resolving FQDNs and HA failovers to occur. For more information: https://docs.paloaltonetworks.com/ngfw/release-notes/12-1/pan-os-12-1-4-known-and-addressed-issues/pan-os-12-1-4-addressed-issues https://docs.paloaltonetworks.com/pan-os/11-1/pan-os-release-notes/pan-os-11-1-13-known-and-addressed-issues/pan-os-11-1-13-addressed-issues https://docs.paloaltonetworks.com/pan-os/11-2/pan-os-release-notes/pan-os-11-2-10-known-and-addressed-issues/pan-os-11-2-10-addressed-issues https://docs.paloaltonetworks.com/pan-os/11-2/pan-os-release-notes/pan-os-11-2-11-known-and-addressed-issues/pan-os-11-2-11-addressed-issues