Hello everyone
To begin with, excuse me for my English because I use the Google translation system.
I am happy to find a forum dedicated to Osclass that I have been using for several years on several French websites.
I encountered a problem when (error 500) when I wanted to update Osclass by following your documentation, it must be said that it is version 3.8.1 that I am using. So if someone could help me update Osclass or point me to a forum post where there is an explanation.
Thank you for your help

Enable error logging and then check error log. Sometimes there is just minor issue or detail with changing some value 

Hello
Thank you for your answer, but I just saw that the content of my site's directories has nothing to do with your version! Here is my oc-include content as an attachment

Yes it is better to remove everything before update from oc-includes folder and replace with new.
This should have no impact on upgrade process, but some files may be redundant