Bug when upgrading site from 3.10 to 4.x

I just tried to update a Joomla 3.10 site with Maximenu CK Pro installed. After the upgrade I installed the Maximenu CK Pro for Joomla 4 - but when I now enter the Maximenu module I get this error:

Call to undefined method Joomla\CMS\Factory::getURI()

??

Hi
Please go in System >> configuration >> site >> debug mode >> set it ON
then you shall have a message about where the error is triggered, please paste it here

CEd

Could the error be because I did not migrate the menu module settings from 8.x to 9.x before the update - then I will just try once again, and migrate before update.

yes, the V8 is not compatible with Joomla 4, you must update it before joomla

Ok - well the extension WAS updated to ver 9 before update, it was just still running in Legacy 8 mode - but that still creates the problem ?

the legacy mode shall not affect the administration of the module ...
have you enabled the debug mode ?
have you followed the instructions to update to the V9 ?
forum.joomlack.fr/index.php/4-maximenu-c...maximenu-ck-v8-to-v9