Hi @ComBak so you are considering an in-place upgrade of the OS to a newer version? Is it a psychical system or virtual? Because, although it is supported to perform an in-place OS upgrade you can never get the guarantee that it will not break anything. So, running it virtually at least allows you to create a snapshot of the VM before starting the upgrade so you have a way to go back easily.
Not sure how big you environment, but as for running the FR20 LTS release I would strongly consider moving to FR24 or even FR28, who are both LTS. By sticking to FR20 you miss a lot of enhancements and updates, especially when it comes to the support of newer application versions.