bulk user import auth0 API - php

Question

i am trying to import users to auth0 using "users import bulk api".
curl_setopt_array($curl, [
CURLOPT_URL => "https://***/api/v2/jobs/users-imports",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
CURLOPT_POSTFIELDS => "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"users\"; filename=\"filename.json\"\r\nContent-Type: text/json\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"connection_id\"\r\n\r\n********\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"external_id\"\r\n\r\n******\r\n-----011000010111000001101001--\r\n",
CURLOPT_HTTPHEADER => [
"authorization: Bearer ".$token."",
"content-type: multipart/form-data; boundary=---011000010111000001101001"
],
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}
i tried to get the file content with stream_get_contents and file_get_contents.
i always get the same error:
{“statusCode”:400," error":“Bad Request”, “message”:“Users file must not be empty.”, “errorCode”:“operation_not_supported”}