Cannot upgrade to 11.4.1

Hi
Trying to upgrade to the new stable version 11.4.1 from the 11.3.2. I get the following errors after replacing the /var/www/projeqtor folder by the new downloaded one :

2024-10-25 08:57:18.136 ***** ERROR ***** [V11.3.2] ERROR *****
2024-10-25 08:57:18.137 ***** ERROR ***** [V11.3.2] on file '/var/www/tool/saveObjectMultiple.php' at line (167)
2024-10-25 08:57:18.137 ***** ERROR ***** [V11.3.2] cause = Undefined property: Activity::$ActivityPlanningElement_validatedEndDate

From the login screen i do have a message stating that the update is in progress, but after more than half an our the update is still not present.
Any idea on what's going wrong ?