Bug ID 650081: Proactive Bot Defense JavaScript challenges may introduce high latencies and cause some browsers to display a blank page.

Last Modified: Nov 07, 2022

Bug Tracker

Affected Product:  See more info
BIG-IP ASM(all modules)

Known Affected Versions:
12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2, 12.1.2, 12.1.2 HF1, 12.1.2 HF2

Fixed In:

Opened: Mar 09, 2017
Severity: 3-Major
Related Article:


When PBD and FP are both enabled, there is a very high client-side latency, especially on Microsoft Internet Explorer version 11 (IE11). On IE11, sometimes the challenge remains on a blank page, never moving on to the site from the back-end server.


Delay or blank page when clients access the page using IE11.


This issue occurs when the following conditions are met: -- Your BIG-IP system has Proactive Bot Defense and fingerprinting enabled. -- The client is using IEll. Note: IE11 is known to be affected by this issue. However, other browsers may also be affected.



Fix Information

Improved the client-side run-time of the JavaScript challenge and prevented it from getting stuck on Internet Explorer.

Behavior Change