Call to undefined function CodeIgniter\Files\finfo_open()

Hello.

When I try to upload a new image and get mimetype, I get errors about finfo_open.

In controller i have: 

Code:

52             $file = $this->request->getFile('userfile');
53             $typeOfFile = $file->getMimeType();

At line 53 it throws an error - "APPPATH/Controllers/Comunitate.php : 53 — CodeIgniter\Files\File->getMimeType ()". 
In SYSTEMPATH/Files/File.php at line 137 I have: Call to undefined function CodeIgniter\Files\finfo_open().

Please help me.