The earliest recollection of this bug is traced back to PAN-OS 11.1.10-h21 - May 15, 2026. This bug is fixed in PAN-OS versions 11.1.14, 11.2.10-h3, 11.1.10-h21, 11.2.11, 11.1.13-h2, 12.1.5. ( Firewalls in HA configurations only ) Fixed an issue where traffic passing through AE layer 2 interfaces was interrupted during HA failovers. ( Firewalls in HA configurations only ) Fixed an issue where traffic passing through AE layer 2 and layer 3 interfaces was interrupted during HA failovers. When LACP pre-negotiation is enabled on firewalls in HA configurations, traffic passing through aggregate Ethernet (AE) interfaces may be interrupted for several minutes during HA failovers. This occurs because the suspended (formerly active) firewall continues to forward packets for active sessions even after the failover completes, causing MAC address flapping on neighboring switches. 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-known-issues https://docs.paloaltonetworks.com/ngfw/release-notes/12-1/pan-os-12-1-5-known-and-addressed-issues/pan-os-12-1-5-addressed-issues https://docs.paloaltonetworks.com/pan-os/11-1/pan-os-release-notes/pan-os-11-1-10-known-and-addressed-issues/pan-os-11-1-10-h21-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-h2-addressed-issues https://docs.paloaltonetworks.com/pan-os/11-1/pan-os-release-notes/pan-os-11-1-14-known-and-addressed-issues/pan-os-11-1-14-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-h3-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