...
This topic provides extra information about and tasks you must perform when upgrading your XperienCentral installation to a specific version. The modifications per version are not cumulative which means that you need to apply the changes for all versions above the one you are upgrading from. For example, if you upgrade from XperienCentral 10.14.0 to 10.21.1, you need to apply the changes described for all versions from 10.14.1 up to and including 10.21.1. For general upgrade information, see Upgrading a Linux Installation or Upgrading a Windows Installation.
...