[Koha] Koha upgrade from 3.20.00.000 (2015) to any latest and stable version

Hello, Our library is planning to upgrade Koha from the version 3.20.00.000 to any Koha latest and stable version. - What Koha version do you recommend us ? - Could you please give us a complete tutorial, system requirements, and the things we have to do (backup ?, etc,) before starting the upgrade ? - Is it possible to upgrade directly from 3.20 (2015) to the latest version ? or we have to upgrade to lower versions before? Given that almost all Koha modules are up-to-date. Best regards, Walid -- *Sultan Qaboos Cultural Center Library* 1100 16th St, NW Washington, DC 20036 library@sqcc.org 202-677-3967, x104