Zend Framework 2: upload and rename multiple files - php

Question

I have a Zend Form and offer the option to upload multiple files with the form. I use dropzone.js. When I upload a single file, everything works fine, I get the Post data and the file gets renamed and moved into the correct folder, but as soon I upload 2 files, I get an Error Message: Notice: Array to string conversion which points to $upload->addFilters('File\Rename'.....
What am I doing wrong here? I have everything in a foreach loop, should this not solve the issue? I can not find a solution for it. Anyone got a tip for me?
Here my Sourcecode so far:
$upload = new \Zend\File\Transfer\Adapter\Http();
// Limit the amount of files
$upload->addValidator('Count', false, 2);
// Limit the MIME type of all given files to gif and jpeg images
$upload->addValidator('MimeType', false, array('image/gif', 'image/jpeg',));
if (!$upload->isValid()) {
$data = new JsonModel(array(
'success' => "failed",
'message' => "validation failed",
));
return $data;
}else{
$files = $upload->getFileInfo();
$upload->setDestination('./public/uploads/tmp/');
// loop through the file array
foreach ($files as $file => $info) {
$file_ext = #strtolower(#strrchr($originalName,"."));
$file_ext = #substr($file_ext, 1); // remove dot
$newFilename = md5(uniqid(rand(), true)) .time(). '.' . $file_ext;
$upload->addFilter('File\Rename',
array('target' => $upload->getDestination() . DIRECTORY_SEPARATOR . $newFilename,
'overwrite' => true));
if (!$upload->receive()) {
$data = new JsonModel(array(
'success' => "upload failed",
));
}else{
$data = new JsonModel(array(
'success' => "upload ok",
));
}
return $data;
} // end foreach
}