It is not possible to create a calendar -> db error 500 (this happens also in wpmaster Civi 6.6)

[Guydn]

WordPress 6.8.2 CiviCRM 6.1.2 EventCalendar 4.6. And also current WPmaster CiviCRM 6.6

I install the extension from extension civiCRM extension screen, activate it, clear the cache, try to create my first Calendar and get this error 500

2748316#2748316: *6300030 FastCGI sent in stderr: "PHP message: PHP Warning: Undefined property: CRM_EventCalendar_Form_EventCalendarSettings::$_gid in /var/aegir/platforms/wordpress-dev/wp-content/plugins/civicrm/civicrm/CRM/Core/Form.php on line 2185;

Same error even if I install the WP plugin.