PHP Core Warning – yii\base\ErrorException

$_GET = [
    'page' => '874',
];

$_COOKIE = [
    '_csrf' => 'e8726cd5310516c111c3bba7ba376037224eb3a71150950a71d4aac6ae0a661ea:2:{i:0;s:5:"_csrf";i:1;s:32:"UI3YLKfOhYcXh06d7srdq3RWw_jCwQ8v";}',
    'viewed' => 'c6256e3c3d27952e9bb4585591b090426c2c94e71f2d317c225b9700fa695aa6a:2:{i:0;s:6:"viewed";i:1;a:1:{i:0;i:159600;}}',
    'PHPSESSID' => '46bhj3vhqf4ffccgebb2jm3vkp',
];

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