ini_set('display_errors', 1); 
# Include the Dropbox SDK libraries
require_once "lib/Dropbox/autoload.php";
use \Dropbox as dbx;
$accessToken = "cBr9qwdqwdqwdqwdqwdZeUHc3YS0fYtrYA"; // Здесь ваш Access token
$dbxClient = new dbx\Client($accessToken, "PHP-Example/1.0");
if($_FILES['ya']['name']){
$f = fopen($_FILES['ya']['name'], "rb");
$fbuch=$_FILES['ya']['name'];
$fbuch2="/".$fbuch;
$fileMetadata = $dbxClient->uploadFile("/ChangeLog.txt", dbx\WriteMode::add(), $f);
fclose($f);
print_r($fileMetadata);}
...
<form action="" method="POST" enctype="multipart/form-data">
<input type = "file" name = "ya" />
<input type="submit" value="Загрузить">
</form>

Fatal error:  Uncaught exception 'InvalidArgumentException' with message ''inStream' has bad type; expecting resource, got boolean' in /var/www/v-2348/data/www/stylus.kz/lib/Dropbox/Checker.php:22
Stack trace:
#0 /var/www/v-2348/data/www/stylus.kz/lib/Dropbox/Checker.php(27): Dropbox\Checker::throwError('inStream', false, 'resource')
#1 /var/www/v-2348/data/www/stylus.kz/lib/Dropbox/Client.php(278): Dropbox\Checker::argResource('inStream', false)
#2 /var/www/v-2348/data/www/stylus.kz/ya.php(16): Dropbox\Client->uploadFile('/Sites.txt', Object(Dropbox\WriteMode), false)
#3 {main}
  thrown in /var/www/v-2348/data/www/stylus.kz/lib/Dropbox/Checker.php on line 22