Hello Arnaud,
For any component, soft, site update use below rules:
Before making any upgrades, make the backup files and Database
At first please check upgrade/update process at the test website!
If you have custom changes of component, you can lose your changes.
Please, in that case do not make update.
If you would like any further information, please do not hesitate to contact us too.
Best Wishes,
Andrew
OrdaSoft team