Last Modified: Sep 01, 2026
Affected Product(s):
BIG-IP TMOS
Known Affected Versions:
17.5.1.6, 17.5.1.8, 21.1.0, 21.1.0.1
Opened: Aug 18, 2026 Severity: 3-Major
The MCPD process logs a configuration exception indicating that a monitor rule cannot be found. This error causes the remote transaction for the device group to fail, impacting failover synchronization between peers.
- Config-sync fails and does not self-heal - The devices remain out of sync
- BIG-IP HA pair with Active-Standby setup, with both devices in sync. - Either a monitor is removed from an FQDN pool on the active device, or another monitor is added to the same FQDN pool on the active device. - Full config-sync runs. The active device pushes changes to the standby device.
- Re-adding the monitor to the active device and then performing the config-sync. or - On the standby device, manually configure the same monitor as the active device. And run config-sync again from the standby device to the active device.
None