I’m not able to trigger a message to a group chat from my Azure-Bot for Microsoft Teams from my PHP application and don’t know why. Tried a lot of things now and asked GPT – but nothing worked. But when I’m using the Botbuilder framework in a javascript environment, the bot answers to my messages.
The credentials are valid and API permissions are also fine. The error I received:

URL: https://smba.trafficmanager.net/emea/v3/conversations/19:[email protected]/activities HTTP response headers: HTTP/1.1 401 Unauthorized Keep-Alive: true Content-Length: 61 Content-Type: application/json; charset=utf-8 Server: Microsoft-HTTPAPI/2.0 MS-CV: VWPVTjV2B0+EmgoDiiux+w.0 Date: Fri, 07 Jun 2024 07:55:01 GMT Connection: close Response: {“message”:”Authorization has been denied for this request.”} Array ( [message] => Authorization has been denied for this request. )

<?php
public function bot_reporting()
    {
        $params = array(
            'tenant_id' => 'xxx',
            'client_id' => 'xxx',
            'client_secret' => 'xxx',
            'bot_service_url' => 'https://smba.trafficmanager.net/emea',
            'chat_id' => '19:[email protected]',
            'bot_id' => 'xxx'
        );
        
        $this->load->library('bot', $params);
        
        try {
            $response = $this->bot->sendMessage('Test!');
            print_r($response);
        } catch (Exception $e) {
            echo 'Error: ' . $e->getMessage();
        }
    }
?>

<?php

defined('BASEPATH') OR exit('No direct script access allowed');

class Bot
{
    protected $ci;
    private $tenantId;
    private $clientId;
    private $clientSecret;
    private $scope;
    private $botServiceUrl;
    private $chatId;
    private $botId;

    public function __construct($params = array())
    {
        $this->ci =& get_instance();

        // Setze die Konfigurationswerte
        $this->tenantId = isset($params['tenant_id']) ? $params['tenant_id'] : '';
        $this->clientId = isset($params['client_id']) ? $params['client_id'] : '';
        $this->clientSecret = isset($params['client_secret']) ? $params['client_secret'] : '';
        $this->scope = 'https://graph.microsoft.com/.default';
        $this->botServiceUrl = isset($params['bot_service_url']) ? $params['bot_service_url'] : '';
        $this->chatId = isset($params['chat_id']) ? $params['chat_id'] : '';
        $this->botId = isset($params['bot_id']) ? $params['bot_id'] : '';
    }

    // Funktion, um ein Access Token von Azure AD zu erhalten
    private function getAccessToken()
    {
        $url = "https://login.microsoftonline.com/{$this->tenantId}/oauth2/v2.0/token";
        $data = array(
            'grant_type' => 'client_credentials',
            'client_id' => $this->clientId,
            'client_secret' => $this->clientSecret,
            'scope' => $this->scope
        );

        $options = array(
            'http' => array(
                'header'  => "Content-type: application/x-www-form-urlencodedrn",
                'method'  => 'POST',
                'content' => http_build_query($data)
            )
        );

        $context  = stream_context_create($options);
        $result = file_get_contents($url, false, $context);

        if ($result === FALSE) { 
            throw new Exception('Error retrieving access token');
        }

        $response = json_decode($result, true);
        if (isset($response['error'])) {
            throw new Exception('Error retrieving access token: ' . $response['error_description']);
        }

        return $response['access_token'];
    }

    // Funktion, um eine Nachricht zu senden
    public function sendMessage($messageContent)
    {
        $accessToken = $this->getAccessToken();

        // Debugging: AccessToken ausgeben
        echo "Access Token: " . $accessToken . "n";

        $url = "{$this->botServiceUrl}/v3/conversations/{$this->chatId}/activities";

        // Debugging: URL ausgeben
        echo "URL: " . $url . "n";

        $data = array(
            'type' => 'message',
            'text' => $messageContent
        );

        $options = array(
            'http' => array(
                'header'  => "Authorization: Bearer $accessTokenrn" .
                             "Content-type: application/jsonrn",
                'method'  => 'POST',
                'content' => json_encode($data),
                'ignore_errors' => true // To capture the response in case of error
            )
        );

        $context  = stream_context_create($options);
        $result = file_get_contents($url, false, $context);
        
        // Capture the HTTP response headers
        $http_response_header = isset($http_response_header) ? $http_response_header : [];

        if ($result === FALSE) { 
            $error = error_get_last();
            echo 'HTTP response headers: ' . implode("n", $http_response_header) . "n";
            throw new Exception('Error sending message: ' . $error['message']);
        }

        echo 'HTTP response headers: ' . implode("n", $http_response_header) . "n";
        echo 'Response: ' . $result . "n";
        
        return json_decode($result, true);
    }
}
?>