Getting "Invalid Argument" Error When Using List User Availability Schedules API

Can you share the details of your request? Please don’t include any personal info or access credentials.

Are you specifying a valid value for the “user” query parameter?

I just tried reproducing the issue with my account and it worked as expected.

Thank you for the quick response!

To give you more details, here’s the flow I’m following:

1. I’ve used OAuth to obtain the authorization code.
2. After that, I retrieved the access token successfully.

Now, I’m trying to get the list of user availability schedules using the API endpoint [https://stoplight.io/mocks/calendly/api-docs/395/user_availability_schedules]. I’m passing the access token from step 2, but I’m encountering two issues:

1. In the API documentation, it asks for a "user ID." I tried using the "Get Current User" API to fetch the ID, but I didn’t receive any user ID in the response. Could you clarify where to get the user ID from?

2. The second issue is the error I’m getting when I try to use the "List User Availability Schedules" API. The error message returned is as follows:

import axios from "axios";

const options = {
  method: 'GET',
  url: 'https://stoplight.io/mocks/calendly/api-docs/395/user_availability_schedules',
  params: {
   user: 'user_id'
  },
  headers: {
       'Content-Type': 'application/json', 
        Authorization: 'Bearer access_token'}
 };

axios.request(options).then(function (response) {
  console.log(response.data);
}).catch(function (error) {
  console.error(error);
});

{
  "title": "Invalid Argument",
  "message": "The supplied parameters are invalid.",
  "details": [
    {
      "parameter": "string",
      "message": "string",
      "code": "string"
    }
  ]
}

Thanks for your response! It's working now.

In your reply, you mentioned that I was using the mock server URL. I tried switching to the live server URI to obtain the access token, but I encountered a 401 error. However, when I send the same request to the mock server, it works fine. Is this expected behavior?

The error message I received was:
"Client authentication failed due to unknown client, no client authentication included, or unsupported authentication method."

I used my Calendly client account for this request.

Here is the code 

    // Base64 encode the credentials
    const authHeader = `Basic ${Buffer.from(
      `${CLIENT_ID}:${CLIENT_SECRET}`
    ).toString("base64")}`;

    // Making the POST request to get the access token
    const options = {
      method: "POST",
      url: "https://auth.calendly.com/oauth/token",
      headers: {
        "Content-Type": "application/x-www-form-urlencoded",
        Authorization: authHeader,
      },
      data: {
        grant_type: "authorization_code",
        code: authorizationCode,
        code_verifier: codeVerifier,
        redirect_uri: REDIRECT_URI,
      },
    };

The mock server can be used to test requests but it doesn’t actually validate your credentials. Instead, it returns predefined responses that you can use to validate your logic. In your case, you need to interact with the live server.

The OAuth used to authenticate and authorize your users actually involves multiple steps. See https://developer.calendly.com/create-a-developer-account for the details, but essentially you have to first register your application, then initiate the OAuth authorization flow (https://developer.calendly.com/api-docs/60a14408d6743-get-authorization-code) and finally retrieve an access token (https://developer.calendly.com/api-docs/be9b32ef4b44c-get-access-token).

My guess is that you are trying to make the last call without having gone through the previous steps.

I don’t know if it applies to your use case, but another option to authenticate requests is using Personal Access Tokens, which involves a much simpler flow. See https://developer.calendly.com/when-to-choose-between-personal-access-tokens-and-oauth to understand if it can be a solution to your problem.

Thank you for the resources! I was able to successfully obtain both the access token and user details.

However, I'm encountering an error when attempting to use the Create One-Off Event Type endpoint. The error message I receive is:

Status 500

{
  title: 'Internal Server Error',
  message: 'The server encountered an unexpected condition that prevented it from fulfilling the request.'
}

Here is the code and data I’m using:

  const data = {
    name: "My Meeting",
    host: uri,
    co_hosts: [],
    duration: 30,
    date_setting: {
      type: "date_range",
      start_date: "2025-2-6", 
      end_date: "2025-3-6", 
    },
    location: {
      kind: "physical",
      location: "Main Office",
      additional_info: "string",
    },
  };

  const options = {
    method: "POST",
    url: "https://api.calendly.com/one_off_event_types",
    headers: {
      "Content-Type": "application/json",
      Authorization: `Bearer ${accessToken}`,
    },
    data,
  };

Glad to hear that you were successful in making authenticated API calls.

Can you please open another thread for the new issue so that it is easier for us to track it and for others to contribute?

Hello,
Can you help plz ?

auth_calendly.php

 

<?php
session_start();
require_once 'vendor/autoload.php';

$dotenv = Dotenv\Dotenv::createImmutable(__DIR__);
$dotenv->load();

// Check if CALENDLY_CLIENT_ID is loaded
if (empty($_ENV['CALENDLY_CLIENT_ID']) || empty($_ENV['CALENDLY_REDIRECT_URI'])) {
    die('❌ Missing CALENDLY_CLIENT_ID or CALENDLY_REDIRECT_URI in .env');
}

// Generate PKCE code verifier and challenge
function generateCodeVerifier() {
    return bin2hex(random_bytes(64)); // 128-character verifier
}

function generateCodeChallenge($verifier) {
    return rtrim(strtr(base64_encode(hash('sha256', $verifier, true)), '+/', '-_'), '=');
}

$code_verifier = generateCodeVerifier();
$code_challenge = generateCodeChallenge($code_verifier);

// Save verifier in session
$_SESSION['calendly_code_verifier'] = $code_verifier;

$client_id = $_ENV['CALENDLY_CLIENT_ID'];
$redirect_uri = urlencode($_ENV['CALENDLY_REDIRECT_URI']);

// Build Calendly auth URL
$auth_url = "https://auth.calendly.com/oauth/authorize?"
    . "response_type=code"
    . "&client_id=$client_id"
    . "&redirect_uri=$redirect_uri"
    . "&scope=default"
    . "&code_challenge=$code_challenge"
    . "&code_challenge_method=S256";

// Redirect to Calendly
header("Location: $auth_url");
exit;
?>


calendly_callback.php

 

<?php
session_start();
require_once 'vendor/autoload.php';

$dotenv = Dotenv\Dotenv::createImmutable(__DIR__);
$dotenv->load();

// ✅ Check for required session & GET param
if (!isset($_GET['code']) || !isset($_SESSION['calendly_code_verifier'])) {
    echo json_encode(['success' => false, 'message' => 'Missing authorization code or code_verifier']);
    exit;
}

$code = $_GET['code'];
$code_verifier = $_SESSION['calendly_code_verifier'];

$client_id = $_ENV['CALENDLY_CLIENT_ID'];
$client_secret = $_ENV['CALENDLY_CLIENT_SECRET'] ?? ''; // OPTIONAL — Calendly does not always provide this
$redirect_uri = $_ENV['CALENDLY_REDIRECT_URI'];

$token_url = 'https://auth.calendly.com/oauth/token';

// 🔐 Base64 encode client_id + client_secret as Basic Auth
$credentials = base64_encode("$client_id:$client_secret");

// 🔁 Prepare request
$ch = curl_init($token_url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    "Authorization: Basic $credentials",
    "Content-Type: application/x-www-form-urlencoded"
]);

curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
    'grant_type' => 'authorization_code',
    'code' => $code,
    'redirect_uri' => $redirect_uri,
    'code_verifier' => $code_verifier
]));

$response = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

$response_data = json_decode($response, true);

if ($http_code !== 200) {
    echo json_encode([
        'success' => false,
        'message' => "Error retrieving Calendly access token. HTTP Code: $http_code",
        'response' => $response_data
    ]);
    exit;
}

// ✅ Save tokens in session
$_SESSION['calendly_access_token'] = $response_data['access_token'];
$_SESSION['calendly_refresh_token'] = $response_data['refresh_token'] ?? null;

// Optional: save in DB if needed
// ...

// Redirect to homepage
header('Location: index.php');
exit;
?>



I get the error :

{"success":false,"message":"Error retrieving Calendly access token. HTTP Code: 401","response":{"error":"invalid_client","error_description":"Client authentication failed due to unknown client, no client authentication included, or unsupported authentication method."}}