This is an old revision of the document!
Older agents from Zabbix 1.x and previous versions of Zabbix 2.x can still be used with Zabbix 3.0. It generally does not require any configuration changes on the agent side, apart from parameters related to logging, which you may want to review.
However, to take full advantage of new and improved items, improved performance and reduced memory usage, use the latest 3.0 agent.
Both Zabbix 3.0 proxies and Zabbix 3.0 server are supported to work only with Zabbix 3.0 server and Zabbix 3.0 proxies respectively.
XML files, exported with 1.8, 2.0, 2.2 and 2.4 are supported for import in Zabbix 3.0.