Bug ID 2047593: Blade upgrade fails with the "HAL unexpected init failure (continuing) : Unknown slot for ChassisBase" error message

Last Modified: Oct 22, 2025

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

Known Affected Versions:
17.5.0, 17.5.1, 17.5.1.2, 17.5.1.3

Opened: Sep 05, 2025

Severity: 2-Critical

Symptoms

C4800 chassis blades at slot positions 5 - 8 fails to join cluster after upgrading to BIG-IP TMOS 17.5.0 with error "Unknown slot for ChassisBase".

Impact

Reduced capacity due to fewer blades joining cluster for traffic handling.

Conditions

C4800 chassis that supports 8 blades with blades at slots 5 to 8 and running with BIG-IP v17.5.0.

Workaround

None

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips