client->upload throws a 'BadRequest'

[rabol]

Hi

I'm trying to upload a file to dropbox
I have created an access token in Dropbox
and use the following code:

$client = new Client($authorizationToken);

$file = 'pdf/' . 'testfile.pdf';
if (Storage::exists($file)) {
    $res = $client->upload('/', Storage::get($file));
} 

it throws a 'Bad Request' exception

Spatie\Dropbox\Client::determineException
vendor/spatie/dropbox-api/src/Client.php:665

Not really sure why