When I launched the update, the system felt and show as if the process wasn't finished. So then my website is out of order and I had to re-implement my back-up via a snapshot of my webhoster.
As the site is hosted by an HDS web-hoster, I try as you told me to set it on a common webhost as OVH in france. The upgrade of the version was then successfull and without problems.
Anyway today my operating site still on 2.5.0+build.2021.04.09.20.27.16.19d16d5eb and I can't try to set the upgrade without trouble making.
At lest the site works fine except for some response to my server which are a bit longer as before. Those problems does'nt occur on my local website nore on my testing site on OVH.
I don't know what is the effective version of the serveur on OVH right now but I do know the version of my operating webserver which is a centOS 7 and PHP 7.3.29 ( I do have a 7.4 PHP on OVH )
Question 1: Do you think that the PHP version could explain the problem by itself ?
Question 2 : Do you see other reasons ?
SereniTeam