Wrong URL ????

hello,

I have built the interface to the "Calendar".

See attachment 1.

The updating of the token when the time has expired is also successfully implemented. (will be automated later in the query)

Only here I have a problem.
https://www.zoho.com/calendar/help/api/get-calendar-list.html

I have attached my PHP code once as a TXT attachment.
As well as its response as an image. Attachment 2:

"Invalid URL

Unable to process your request as the URL /calendar/api/v1/calendars?category=all&showhiddencal=true is invalid."

What am I doing wrong or is the documentation no longer correct?

Many thanks for your help.

<?php

function fetch_and_renew_token() {
    $client_id = NMT::sqlObject("SELECT `val` FROM `nmt-cfg` WHERE `key` = 'zoho_client_id'; ")->val;
    $client_secret = NMT::sqlObject("SELECT `val` FROM `nmt-cfg` WHERE `key` = 'zoho_client_secret'; ")->val;
    $refresh_token = NMT::sqlObject("SELECT `val` FROM `nmt-cfg` WHERE `key` = 'zoho_refresh_token'; ")->val;

    if (!empty($client_id) && !empty($client_secret) && !empty($refresh_token)) {
        $url = 'https://accounts.zoho.eu/oauth/v2/token';
        $data = [
            'refresh_token' => $refresh_token,
            'client_id' => $client_id,
            'client_secret' => $client_secret,
            'grant_type' => 'refresh_token'
        ];

        $response = custom_curl_request($url, $data);

        if (isset($response['access_token'])) {
            $access_token = $response['access_token'];
            $expires_in = $response['expires_in'];
            $api_domain = $response['api_domain'];
            $expires_at = time() + $expires_in + 7200; // +2 Stunden

            NMT::sqlDo("INSERT INTO `nmt-cfg` (`key`, `val`) VALUES ('zoho_access_token', '$access_token') ON DUPLICATE KEY UPDATE `val` = '$access_token';");
            NMT::sqlDo("INSERT INTO `nmt-cfg` (`key`, `val`) VALUES ('zoho_token_expires_at', '$expires_at') ON DUPLICATE KEY UPDATE `val` = '$expires_at';");
            NMT::sqlDo("INSERT INTO `nmt-cfg` (`key`, `val`) VALUES ('zoho_api_domain', '$api_domain') ON DUPLICATE KEY UPDATE `val` = '$api_domain';");

            return $access_token;
        } else {
            echo '<div style="color: red;">Fehler bei der Token-Erneuerung.</div>';
            echo '<pre>' . print_r($response, true) . '</pre>';
            return null;
        }
    } else {
        echo '<div style="color: red;">Fehler: Client ID, Client Secret oder Refresh Token fehlen.</div>';
        return null;
    }
}

function custom_curl_request($url, $data = [], $type = 'POST', $headers = []) {
    $curlOpts = [
        CURLOPT_URL => $url,
        CURLOPT_RETURNTRANSFER => TRUE,
        CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_2TLS,
        CURLOPT_CUSTOMREQUEST => $type,
        CURLOPT_SSL_VERIFYPEER => FALSE,
    ];

    if ($type === 'POST' && !empty($data)) {
        $curlOpts[CURLOPT_POSTFIELDS] = http_build_query($data);
    }

    if (!empty($headers)) {
        $curlOpts[CURLOPT_HTTPHEADER] = $headers;
    }

    $request = curl_init();
    curl_setopt_array($request, $curlOpts);
    $response = curl_exec($request);
    $curl_error = curl_error($request);
    $http_code = curl_getinfo($request, CURLINFO_HTTP_CODE);
    curl_close($request);

    if ($curl_error) {
        echo '<div style="color: red;">Curl Error: ' . htmlspecialchars($curl_error) . '</div>';
    }

    echo '<div>HTTP Code: ' . htmlspecialchars($http_code) . '</div>';
    echo '<div>Request URL: ' . htmlspecialchars($url) . '</div>';
    echo '<div>Request Headers: ' . htmlspecialchars(print_r($headers, true)) . '</div>';

    if ($http_code >= 400 && $http_code < 600) {
        echo '<div>Raw Response: ' . $response . '</div>';
    } else {
        echo '<div>Raw Response: ' . htmlspecialchars($response) . '</div>';
    }

    return json_decode($response, TRUE);
}

function fetch_calendars() {
    $access_token = NMT::sqlObject("SELECT `val` FROM `nmt-cfg` WHERE `key` = 'zoho_access_token'; ")->val;
    $api_domain = NMT::sqlObject("SELECT `val` FROM `nmt-cfg` WHERE `key` = 'zoho_api_domain'; ")->val;

    if (!empty($access_token) && !empty($api_domain)) {
        echo '<div>Verwendeter Access Token: ' . htmlspecialchars($access_token) . '</div>';
        echo '<div>Verwendete API Domain: ' . htmlspecialchars($api_domain) . '</div>';

        $url = $api_domain . '/calendar/api/v1/calendars?category=all&showhiddencal=true';
        $headers = [
            "Authorization: Bearer $access_token"
        ];

        $curl_command = "curl -X GET \"$url\" -H \"Authorization: Bearer $access_token\"";
        echo '<div>Curl Command: ' . htmlspecialchars($curl_command) . '</div>';

        $response = custom_curl_request($url, [], 'GET', $headers);

        if (isset($response['calendars'])) {
            echo '<div>Kalender erfolgreich abgerufen:</div>';
            echo '<pre>' . print_r($response['calendars'], true) . '</pre>';
        } else {
            echo '<div style="color: red;">Fehler beim Abrufen der Kalender.</div>';
            echo '<pre>' . print_r($response, true) . '</pre>';
        }
    } else {
        echo '<div style="color: red;">Fehler: Access Token oder API Domain fehlt.</div>';
    }
}

if (isset($_POST['fetch_calendars'])) {
    fetch_calendars();
}

if (isset($_POST['fetch_token'])) {
    fetch_and_renew_token();
}
?>

<form method="post" action="">
    <input type="submit" name="fetch_token" value="Fetch-Token" />
    <input type="submit" name="fetch_calendars" value="Kalender abfragen" />
</form>