Bug ID 1399369: While upgrading standby device, active device is going to standby mode for few seconds, and traffic loss is observed. ... Last Modified: Sep 01, 2025 ... Affected Product(s): ... Traffic loss due to failover. ... Impact ... Traffic loss lasting up to 20 seconds approx. ... Conditions ... -- F5OS with BIG-IP tenants. -- Execute failovers on the active device by running "tmsh run sys failover standby". -- Proceed to upgrade F5OS on the current standby device. -- Note that during this process, the device previously in Active mode will transition to standby mode momentarily, typically lasting around 20 seconds. ... Workaround ... None