here is the error code I have when I run install.php

@JugurthaK How exactly are you trying to do the update? Did you click the auto update button in UI or did you execute a ./console core:update?

I'm using a deployment system, so I downloaded the new archive, unzip it, creating my own config.ini.php then running a script (called install.php) to install everything.

what exactly is the install.php script doing? maybe you could paste it's content.
Normally it should be enough to replace all the files and execute a ./console core:update afterwards to do an update.

https://gist.github.com/JugurthaK/2cfe4b74c26e6880ae515ae807e0890d

There is the install.php script. As you can see on line 273, its already doing a ../console core:update

But besides copying the files only a ./console core:update should be needed. Haven't looked at the whole script, but it seems to do a lot stuff that is not needed...

So, you advice me to only do a ./console core:update, or should I download the new archive before ?

you need to download the archive before and replace all files with the contents of it. The only file you need to keep from the old install is your config.ini.php. Afterwards you can run a ./console core:update

The ./console core:update returns a warning to activate the Login plugin (because we're using Ldap Login by default), I did it and after that its telling me Everything is already up to date.

./console core:update will only do anything if database updates are required or any other operation needs to be done in order to update anything. If it doesn't do anything, that means the last update didn't include such changes.

See https://matomo.org/docs/update for more information on how to update Matomo