I have installed and enabled [BBcode](https://www.drupal.org/project/bbcode), [BUEditor](https://www.drupal.org/project/bueditor), [Extensible BBcode](https://www.drupal.org/project/xbbcode) and [Advanced Forum](https://www.drupal.org/project/advanced_forum) modules on my site. I would like use BBcodes to post the topics in forum. When I post the topic with any value [for e.g [b]this is a test data[/b]] and submit the posting I see the raw data displayed without BBcode formatting.

Not sure what is going wrong. I see the errors in the drupal logs.

> Warning: preg_match_all(): Compilation failed: unrecognized character
> after (?< at offset 5 in XBBCodeFilter->process() (line 42 of
> /var/web/sites/all/modules/xbbcode/xbbcode.filter.inc).

Appreciate your help.

Thanks