OK. First method didn't work. Second method is not same as you say.. I don't have any wp_options in db. But I have wph1_options (everything start with wph1 here) and under wph1_options there is nothing called ''wpforo_forum_tree''.

If you wish please contact me via email or give me a support email so I can provide you the panel password for you to check.

Thank you.

wp_ is just a default WordPress database table prefix, it doesn't matter your tables prefix is wp_ or wxp_ or something else. I see problem in server output buffering functions. It doesn't generate data for this option. We'll add some changes in next wpForo version to addapt it for hsting servers like yours. Currently I recommend to do a small change in core files. Please open /wpforo/wpf-includes/class-forums.php file and find this line:

if( !wpforo_is_admin() ){

Change to this:

if( false ){

I did the change. Well seems like all I can do is waiting for the new update. Thanks.

This is not a bug and this will never be fixed in update, this is site specific issue cased by incomplete installation. I think wpForo is damaged on your website. The only way to debug is having admin access. Please send it to support[at]gvectors.com email address. We'll check it within next 12-24 hours.

Thank you.. sending you the information now.