Symfony\Component\Finder\Finder::ignoreUnreadableDirs PHP Method

    public function ignoreUnreadableDirs($ignore = true)
    {
        $this->ignoreUnreadableDirs = (bool) $ignore;

        return $this;
    }

 /**
  * @inheritdoc
  */
 public function searchString($stringToSearch, $searchFolder)
 {
     $this->finder = $this->finderFactory->create();
     $result = new FileSearchResult($searchFolder);
     $this->finder->ignoreUnreadableDirs()->in($searchFolder);
     foreach ($this->finder->files()->contains($stringToSearch) as $file) {
         /** @var \Symfony\Component\Finder\SplFileInfo $file */
         $fileLocation = new FileLocation();
         $fileLocation->setFolder($file->getPath());
         $fileLocation->setName($file->getFilename());
         $fileLocation->setExtension($file->getExtension());
         $result->add($fileLocation);
     }
     return $result;
 }