Bug ID 1983553: Unable to load config after upgrading to v17.1.x or v17.5.x with the Syntax Error: "tcp-ack-flood" unknown property

Last Modified: Feb 03, 2026

Affected Product(s):
BIG-IP AFM, Install/Upgrade(all modules)

Known Affected Versions:
17.1.0, 17.1.0.1, 17.1.0.2, 17.1.0.3, 17.1.1, 17.1.1.1, 17.1.1.2, 17.1.1.3, 17.1.1.4, 17.1.2, 17.1.2.1, 17.1.2.2, 17.1.3, 17.1.3.1, 17.5.0, 17.5.1, 17.5.1.2, 17.5.1.3, 17.5.1.4

Opened: Jul 16, 2025

Severity: 2-Critical

Symptoms

After upgrading a BIG-IP AFM device from version 16.1.5.1 to 17.1.x or 17.5.x, the device fails to come online. Syntax Error:(/config/bigip.conf at line: 2737) "tcp-ack-flood" unknown property

Impact

Config load fails after the reboot. The system fails to come online and become active.

Conditions

-- In the configuration, "security dos device-config dynamic-signatures network detection" is enabled. -- An upgrade occurs

Workaround

-- Manually find and remove the duplicate state entry in bigip.conf. -- Perform "tmsh load sys config verify" or reboot

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips