How to revert the Jenkins setup if plugin/Jenkins updates went wrong.
As Tensibai mentioned in the comment - better way is backup you Jenkins instance before an update

There are different ways to do this:

Plugins

Jenkins has a lot of backup plugins, most popular is:

PeriodicBackup Plugin - be aware, has status This plugin is up for adoption right now, that means there is can be lack of support

thinBackup Plugin - the same about current status of plugin

SCM Sync configuration plugin - see attention on the plugin page, this is deprecated plugin, the suggestion about migrate their jobs to Pipeline Plugin and use the Configuration as Code Plugin also make sense

All of them easy to use, also you can discovery any Jenkins plugin here

Your own solution

Jenkins has good structure for backup, it is not hard to understand what exactly you need to backup and how.

You can write script\job with simple steps copy, archive, move to achieve backup of your Jenkins.

More information and discussion about how to backup jenkins can be found here: How do you back up Jenkins jobs &amp; master configs?

As for me

I'm using Periodic Backup plugin + my own scripts for transfering backups into different places. But this plugin is not really stable and has opened issues, so i'm not recommend this for highload production use. That's fine for personal not-critical systems. Now I decided to migrate to my own solution with simple job to archive and copy all configs of my Jenkins instances.