How do I save uploaded file permanently in file_manged table?
Thank you @Clive &amp;  @kiamlaluno

/* Fetch the array of the file stored temporarily in database */ 
   $image = $form_state-&gt;getValue('image');

/* Load the object of the file by it's fid */ 
   $file = File::load( $image[0] );

/* Set the status flag permanent of the file object */
   $file-&gt;setPermanent();

/* Save the file in database */
   $file-&gt;save();