The earliest recollection of this bug is traced back to PAN-OS 8.1.5 - January 09, 2024. This bug is fixed in PAN-OS versions 8.1.5. ( The following PA-7000 Series NPCs only: PA-7000-20G-NPC, PA-7000-20GQ-NPC, PA-7000-20GXM-NPC, PA-7000-20GQXM-NPC ) Fixed an issue where an egress buffer overflow that impacted internal packet path monitoring caused a high availability (HA) failover. Additionally, enhancements were made to flow control communication between the traffic manager and flow engine components to improve system stability during periods of heavy traffic. For more information: https://docs.paloaltonetworks.com/pan-os/8-1/pan-os-release-notes/pan-os-8-1-addressed-issues/pan-os-8-1-5-addressed-issues