PHP Core Warning – yii\base\ErrorException

$_GET = [
    'category' => 'vanna',
];

$_COOKIE = [
    '_csrf' => '5ed189bd4286f1df90eb729a180acff7b64696ca059dee1a0f6d183f958f7327a:2:{i:0;s:5:"_csrf";i:1;s:32:"Dv2G1gOcVS7_ku4EEwNyGmZdpnOnhotR";}',
    'PHPSESSID' => 'ru7e1at4fibjtj0ptbjqp8rkp4',
    '_language' => '4f1c89ec35626f051bd177d8c826ebc0bbc5ddb4217dae6ef59531dad3f5ff8ea:2:{i:0;s:9:"_language";i:1;s:2:"uk";}',
];

$_SESSION = [
    '__flash' => [],
    '_language' => 'uk',
];