hello, I downgrade to V7.4.2, it's works ! Now, I can create activity.

I have just a mistake now on V7.4.2, I have loose the picture of each ressources, maybe I need to copy a folder of the V7.4.3 backup, but I don't know which folder ?

Hi,
This conforms your migration process is not as expected.
Process is to overwrite existing code with new one, then reconnect as admin, and migration is seamless.
You can copy the directory (and of course backup db) before, but you must migrate original directory, not the copy.
Images are in attachments.

A patch is provided on thread : https://www.projeqtor.org/fr/forum-fr/2-submit-issues/9885-solved-empty-project-automaticaly-created-after-activity-creation