• i have topic prefix v3.2.3
• indeed disabling it doesn't crash anymore wordpress

the change log between 3.2.3 to 3.2.4 doesn't seem to be around fixing this. 

So whatever changes happen in the meantime they are not backward compatible causing the crash of wordpress and the plug-in became useless for me, unfortunately.  

Regards!

This issue should not have any relation to 2.2.7. I see the issue comes from either file system or topic prefix addon. Please try to disable the topic prefix addon and test it again.

Also, please let me know the version of topic prefix plugin you use.

• i've upgraded to 2.2.7
• caches flushed
• and created second new board

During the board save wordpress crashed. 

any attempt to view, edit, or delete this newly created board crashes WordPress. Orginal 1st board works.

Here is what was captured.

Error type E_ERROR caused by in line 1435 pliku /srv/www/abcd/wp-content/plugins/wpforo/includes/functions.php. Error: Uncaught TypeError: wpforo_write_file(): Argument #2 ($content) must be of type string, null given, called in /srv/www/abcd/wp-content/plugins/wpforo/includes/functions.php on line 2248 and defined in /srv/www/abcd/wp-content/plugins/wpforo/includes/functions.php:1435
Stack trace:
#0 /srv/www/abcd/wp-content/plugins/wpforo/includes/functions.php(2248): wpforo_write_file()
#1 /srv/www/abcd/wp-content/plugins/wpforo-topic-prefix/includes/functions.php(55): wpforo_get_option()
#2 /srv/www/abcd/wp-content/plugins/wpforo-topic-prefix/includes/functions.php(4): wpforotpx_activation()
#3 /srv/www/abcd/wp-includes/class-wp-hook.php(324): {closure}()
#4 /srv/www/abcd/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#5 /srv/www/abcd/wp-includes/plugin.php(517): WP_Hook->do_action()
#6 /srv/www/abcd/wp-content/plugins/wpforo/wpforo.php(529): do_action()
#7 /srv/www/abcd/wp-includes/class-wp-hook.php(324): wpforo\wpforo->init()
#8 /srv/www/abcd/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters()
#9 /srv/www/abcd/wp-includes/plugin.php(517): WP_Hook->do_action()
#10 /srv/www/abcd/wp-settings.php(643): do_action()
#11 /srv/www/abcd/wp-config.php(90): require_once('...')
#12 /srv/www/abcd/wp-load.php(50): require_once('...')
#13 /srv/www/abcd/wp-admin/admin.php(34): require_once('...')
#14 {main}
  thrown

Any idea how to fix it? 

any watchouts if the only way is to start trying to remove/updates records in database?

Cheers