Translations:Manual:Upgrading/42/en

You should put the decompressed tarball in a new and empty folder on your server. If you instead extract the new version directly on top of your old version, rather than in a new directory, you should follow the instructions described in Back up existing files and the database: otherwise, if you've made any customizations you may erase them in a way that leaves you with no reference to re-apply them from.