Item key helper - the dialog that allows to choose from the built-in item keys - can now be translated.
Starting from 2.2.1 the PHP gettext extension is not a mandatory requirement for installing Zabbix. If gettext is not installed, the frontend will work as usual, but the translations will not be available.
The global housekeeping settings have been changed to allow to override the history storage period even if internal housekeeping is disabled. Now, when using an external housekeeper, the history storage period should be set using the history “Data storage period” field instead of the ZBX_HISTORY_DATA_UPKEEP constant.
If trend storage period is set to zero for an item or globally in the housekeeping settings, the frontend will no longer try to render graphs from trend data, but will use history data instead.