problem after upgrade site to joomla 4.0

Hi,
This evening trying to update my site to joomla 4.0, after update i get the error "Cannot access protected property Joomla\CMS\Menu\MenuItem::$params" . Already , changed "$menuitem->getParams();" in title.php , but error is still there.
The site is using template doctor - helix 3 - php 8.0 (also tried with php 7.4 but same error). The old site on joomla 3.10 works , also with php 8.0
Could you help to inform how i can resolve this problem.
Thank you,
Ignace