sorry, for me this is not a very big problem
i added the 2 codes and everything works fine
Thanks tutrix, and I understand, by adding the code everything works.
As for me, I want to establish what the root cause of the problem is. I do not want to start adding code as workaround to fix every potential bug.
So I'll keep digging. 🙂
I found the problem.
The fact is that WPFORO changed their add_action hook from init to admin_bar_init in 38 line of wpf-includes/wpf-hooks.php
To make a long story short,
due to the load order of show_admin_bar(false), the _admin_bar_bump_cb is loaded.
I don't know the reason WPFORO changed the action hook. Is add_action on 'init' bad behavior?