Yii2 why data is not written to cache?

Question

Yii

Added to the components section:

'cache' => [
    'class' => 'yii\caching\FileCache',
 ],

A simple example of the form does not work:

$data = \Yii::$app->cache->get('key_name');
if ($data === false) {
    $a = \Yii::$app->cache->add('key_name', "value", 60);
}

In this example, $a always returns true, but $data is always false. There is silence in PHP and Yii2 logs. Folders with files are created in the runtime/cache folder. What could be the problem?
UPDATE: Problem solved, answer below.

Answer 1

The problem was in synchronizing the files of the guest machine with the host. Under this case, vagrant-winnfsd was installed in Vagrant. Demolished the plugin, everything is in order.

Answer 2

// add()	Stores a value identified by a key into cache if the cache does not contain this key.
$a = \Yii::$app->cache->add('key_name', "value", 60);

Why not use the SET method - it doesn't look at anything - it just creates a key/value.