Disclaimer

Known affected versions were inferred from fixed-version data and were not explicitly confirmed by the vendor: 8.1.8-h5

The earliest recollection of this bug is traced back to PAN-OS 8.1 - July 22, 2025. This bug is fixed in PAN-OS versions 8.1.9. ( PAN-OS 8.1.7 & 8.1.8 only ) Fixed an issue where AUX ports remained in Down state after you upgraded to PAN-OS 8.1.7. ( PAN-OS 8.1.7 and PAN-OS 8.1.8 only ) If you use the AUX 1 or AUX 2 interface and you do not configure an IP address, network mask, and default gateway for the interface, the interface will not come up when you upgrade the firewall to PAN-OS 8.1.7. The most common use of AUX interfaces is to configure AUX ports as HA1 and HA1 Backup interfaces for fiber connections on PA-5200 Series firewalls in an HA configuration. Workaround: To avoid a split-brain scenario in HA configurations as a result of this issue, configure a default gateway on at least one of the AUX interfaces. For more information: https://docs.paloaltonetworks.com/pan-os/8-1/pan-os-release-notes/pan-os-8-1-addressed-issues/pan-os-8-1-9-addressed-issues https://docs.paloaltonetworks.com/pan-os/8-1/pan-os-release-notes/pan-os-8-1-release-information/known-issues/known-issues-related-to-pan-os-8-1-releases