Sending VTT file for Captions and Receiving 10004 Decoding Error

Using Laravel/PHP/Guzzle to update the captions file and receiving this error, wondering if you see anything off with this:

Client error: PUT https://api.cloudflare.com/client/v4/accounts/345345345345345345345/stream/345345345345345345/captions/enresulted in a400 Bad Request response: { "result": null, "success": false, "errors": [ { "code": 10004, "message": "Decoding Error" }

CODE:

private $account_id = "345345345345345345";
    private $headers = [
        "X-Auth-Email" => "[email protected]",
        "X-Auth-Key" => "345345345345"
    ];

$client = new Client();

        $uri = "https://api.cloudflare.com/client/v4/accounts/" . $this->account_id . "/stream/" . $cloudflare_id . "/captions/en";

        $response = $client->request('PUT', $uri, [
            'headers' => $this->headers,
            'multipart' => [
                [
                    'name'     => $file,
                    'contents' => Storage::get($directory . $file)
                ]
            ]
        ]);