@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
@Defaultuser do you have the plugin nodebb-plugin-dbsearch activated?
I believe links to email confirmation expire after certain time (need to confirm). Create a new user and try to verify it right away.
I activated the search plugin. It works.
I made a test account and still get that error. Also my admin account gets this error. I sent receive the email as soon as I login and the pop up asking to confirm it.
*Edit trying to replace the nodebb logo in settings ends up have my logo and nodebb, where is the is the nodebb logo so I can replace it?