Background processes error after upgrade

[kRSB]

Hello, after upgrading from 4.1.12 to 4.1.13.2 i can't run the background processes anymore on my test site (i'm stuck on 87% of rebuidling posts)

this is the sql error i get:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IS NULL ORDER BY pid DESC LIMIT 0,50' at line 1
SELECT * FROM `forums_posts` WHERE pid < IS NULL ORDER BY pid DESC LIMIT 0,50

backtrace:

#0 /Applications/AMPPS/www/forums/system/Db/Exception.php(109): IPS\_Log::log('You have an err...', 'sql')
#1 /Applications/AMPPS/www/forums/system/Db/Db.php(388): IPS\Db\_Exception->__construct('You have an err...', 1064, NULL, 'SELECT * FROM `...', Array)
#2 /Applications/AMPPS/www/forums/system/Db/Select.php(346): IPS\_Db->preparedQuery('SELECT * FROM `...', Array)
#3 /Applications/AMPPS/www/forums/system/Db/Select.php(408): IPS\Db\_Select->runQuery()
#4 [internal function]: IPS\Db\_Select->rewind()
#5 /Applications/AMPPS/www/forums/applications/core/extensions/core/Queue/RebuildPosts.php(98): IteratorIterator->rewind()
#6 /Applications/AMPPS/www/forums/system/Task/Task.php(48): IPS\core\extensions\core\Queue\_RebuildPosts->run(Array, 1542327)
#7 /Applications/AMPPS/www/forums/applications/core/modules/admin/system/background.php(76): IPS\_Task::runQueue()
#8 [internal function]: IPS\core\modules\admin\system\_background->IPS\core\modules\admin\system\{closure}(Array)
#9 /Applications/AMPPS/www/forums/system/Helpers/MultipleRedirect/MultipleRedirect.php(71): call_user_func(Object(Closure), Array)
#10 /Applications/AMPPS/www/forums/applications/core/modules/admin/system/background.php(123): IPS\Helpers\_MultipleRedirect->__construct(Object(IPS\Http\Url), Object(Closure), Object(Closure))
#11 [internal function]: IPS\core\modules\admin\system\_background->process()
#12 /Applications/AMPPS/www/forums/system/Dispatcher/Controller.php(85): call_user_func(Array)
#13 /Applications/AMPPS/www/forums/applications/core/modules/admin/system/background.php(33): IPS\Dispatcher\_Controller->execute()
#14 /Applications/AMPPS/www/forums/system/Dispatcher/Dispatcher.php(129): IPS\core\modules\admin\system\_background->execute()
#15 /Applications/AMPPS/www/forums/admin/index.php(13): IPS\_Dispatcher->run()
#16 {main}

 

I also get it when i manually go to tasks in ACP -> start queue task.

Thanks in advance!