Fatal error: Uncaught Error: Interface 'JsonSerializable' not found in /var/www/vhosts/ijser.aliraqia.edu.iq/httpdocs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Support/Fluent.php:10 Stack trace: #0 /var/www/vhosts/ijser.aliraqia.edu.iq/httpdocs/lib/pkp/lib/vendor/composer/ClassLoader.php(576): include() #1 /var/www/vhosts/ijser.aliraqia.edu.iq/httpdocs/lib/pkp/lib/vendor/composer/ClassLoader.php(427): Composer\Autoload\{closure}() #2 [internal function]: Composer\Autoload\ClassLoader->loadClass() #3 /var/www/vhosts/ijser.aliraqia.edu.iq/httpdocs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Support/Traits/CapsuleManagerTrait.php(35): spl_autoload_call() #4 /var/www/vhosts/ijser.aliraqia.edu.iq/httpdocs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Database/Capsule/Manager.php(32): Illuminate\Database\Capsule\Manager->setupContainer() #5 /var/www/vhosts/ijser.aliraqia.edu.iq/httpdocs/lib/pkp/classes/core/PKPApplication.inc.php(206): Illuminate\Database\Capsule\Manager->__construct() #6 /var/www/vhosts in /var/www/vhosts/ijser.aliraqia.edu.iq/httpdocs/lib/pkp/lib/vendor/laravel/framework/src/Illuminate/Support/Fluent.php on line 10