I updated to IPB 4.12.1 and AT&P 3.1.6 and I always get this error when editing a forum in ACP:
ErrorException: Parameter 1 to IPS\forums\advancedtagsprefixes_hook_forumLastPostPrefix::form() expected to be a reference, value given (2)
#0 [internal function]: IPS\IPS::errorHandler(2, 'Parameter 1 to ...', '/web...', 14, Array)
#1 /web/domain.com/public_html/init.php(434) : eval()'d code(14): call_user_func_array('parent::form', Array)
#2 /web/domain.com/public_html/system/Node/Controller.php(452): IPS\forums\hook174->form(Object(IPS\Helpers\Form))
#3 /web/domain.com/public_html/init.php(434) : eval()'d code(13): IPS\Node\_Controller->_addEditForm(Object(IPS\forums\Forum))
#4 /web/domain.com/public_html/system/Node/Controller.php(351): IPS\Node\advancedtagsprefixes_hook_nodeSettings->_addEditForm(Object(IPS\forums\Forum))
#5 /web/domain.com/public_html/applications/forums/modules/admin/forums/forums.php(124): IPS\Node\_Controller->form()
#6 [internal function]: IPS\forums\modules\admin\forums\_forums->form()
#7 /web/domain.com/public_html/system/Dispatcher/Controller.php(85): call_user_func(Array)
#8 [internal function]: IPS\Dispatcher\_Controller->execute()
#9 /web/domain.com/public_html/init.php(434) : eval()'d code(14): call_user_func_array('parent::execute', Array)
#10 /web/domain.com/public_html/system/Node/Controller.php(63): IPS\Dispatcher\hook158->execute()
#11 /web/domain.com/public_html/applications/forums/modules/admin/forums/forums.php(40): IPS\Node\_Controller->execute()
#12 /web/domain.com/public_html/system/Dispatcher/Dispatcher.php(129): IPS\forums\modules\admin\forums\_forums->execute()
#13 /web/domain.com/public_html/Comft/index.php(13): IPS\_Dispatcher->run()
#14 {main}
I have Pre-Defined Topic fiends installed also along with this.