KBI 311278 Issue Addressed: Argent Defender Web Session Script Might Fail Random When Encountering Hidden Blank Page


Argent Advanced Technology all versions


Thursday, 3 September 2015


Argent Defender web session script can randomly fail on some websites

Inspecting the task log, customer can see lines like following:

IGNORED hidden about:blank page

>>>> Unhandled Exception happened in Thread

The issue has been seen in IE 10 and above, but not IE 9 or earlier version

The issue has addressed in Argent Advanced Technology 3.1A-1507-T3

Technical Background

Argent Defender runs web session script by driving MSHTML interface

However, if the driver runs in a different worker thread from the page is running, random exception error can be resulted

IE 10 and later version may generate some hidden pages ‘about:blank’ for some undocumented purposes

The blank page may be sitting on the top of page stack and it runs in its own worker thread

When Argent Defender Engine touches the MSHTML interface of visible page from the worker thread of blank page, exception error can happen and web session script fails

Argent Defender 3.1A-1507-T3 has been enhanced to make sure driver code runs in the same worker thread as the target page


Upgrade to Argent AT 3.1A-1507-T3 or later