Undefined array key "user_auth_key"

[imrostom]

I face this issue when send push notifiation based on this,

OneSignal::sendNotificationToUser($message, $tokens, route('admin.ticket.show', $ticket));

[GalahadXVI]

Make sure you have user_auth_key defined in services.php

    'onesignal' => [
        'app_id' => env('ONESIGNAL_APP_ID'),
        'rest_api_key' => env('ONESIGNAL_REST_API_KEY'),
        'user_auth_key' => env('ONESIGNAL_USER_AUTH_KEY'),
        'guzzle_client_timeout' => env('ONESIGNAL_GUZZLE_CLIENT_TIMEOUT', 60),
    ],