@gotwf 9.5 (Ya I know is a very old version 😑 )
@hnahli you'll want to make a database dump, depending on your db it's different just search
[your db] dump backup.
You'll also want to make a backup of your uploaded files if any.
Here's an okay resource: https://docs.nodebb.org/fr/latest/upgrading/index.html?highlight=backup#back-up-your-data