Amazon S3 Multiple Part Upload Returns NULL - php

Question

I am trying to upload an 8GB file, but it constantly returns null. I also do not get an error message no exceptions thrown. The null is displayed in the va_dump, the normal s3 -> putObject works fine with files under 5GB. My code is the following:
$s3 = S3Client::factory(array(
'credentials' => array(
'secret' => 'xxx',
'key' => 'xxxxx'
),
'region' => 'us-west-2',
'version' => '2006-03-01'
));;
try {
if(filesize($body) < 5000000000) {
$result = $s3->putObject(array(
'Bucket' => $bucket,
'Key' => $obect,
'SourceFile' => $body,
'ContentType' => $content_type,
'ACL' => $acl,
));
return $result['ObjectURL'];
} else {
echo 'Starting Uploads';
$source = fopen($body, 'rb');
$uploader = new MultipartUploader($s3, $source
, [
'bucket' => $bucket,
'key' => $obect,
'acl' => $acl,
'concurrency' => 5,
'part_size' => (100 * 1024 * 1024),
'before_initiate' => function(\Aws\Command $command) use ($content_type) {
$command['ContentType'] = $content_type; // video/mp4
}
]);
echo 'Into Upload';
$result = $uploader->upload();
echo 'Complete Upload';
var_dump($result);
return (isset($result['Location'])) ? $result['Location'] : false;
}
} catch (MultipartUploadException $e) {
error_log($e -> getMessage() . ' ' . $e -> getTraceAsString());
$uploader = new \Aws\S3\MultipartUploader($s3, $body, [
'state' => $e->getState(),
]);
return false;
} catch (Aws\Exception\S3Exception $e) {
error_log($e -> getMessage() . ' ' . $e -> getTraceAsString());
return false;
} catch (Exception $e) {
error_log($e -> getMessage() . ' ' . $e -> getTraceAsString());
return false;
}
return false;