Had a look at Nginx error.log. Found something interesting.
2016/09/22 00:30:53 [error] 16719#16719: *34 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught Error: Call to a member function until() on null in /var/www/html/vendor/flarum/core/src/Database/AbstractModel.php:126
Stack trace:
#0 /var/www/html/vendor/flarum/core/src/Database/AbstractModel.php(182): Flarum\Database\AbstractModel->getCustomRelation('whereRaw')
#1 [internal function]: Flarum\Database\AbstractModel->call('whereRaw', Array)
#2 /var/www/html/vendor/illuminate/database/Eloquent/Model.php(3458): call_user_func_array(Array, Array)
#3 /var/www/html/vendor/flarum/core/src/Http/AbstractServer.php(50): Illuminate\Database\Eloquent\Model::callStatic('whereRaw', Array)
#4 /var/www/html/vendor/flarum/core/src/Http/AbstractServer.php(27): Flarum\Http\AbstractServer->collectGarbage(Object(Flarum\Foundation\Application))
#5 /var/www/html/index.php(16): Flarum\Http\AbstractServer->listen()
#6 {main}
thrown in /var/www/html/vendor/flarum/core/src/Database/AbstractModel.php on line 126" while reading response header from upstream, client: 10.10.20.10, server: _, request: "GET / HTTP/1.0", upstream: "fastcgi://unix:/run/php/php7.0-fpm.sock:", host: "goaitforum.com"
