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These notes are for upgrading from Zabbix 4.0.x to Zabbix 4.2.0. All notes are grouped into:
Critical- the most critical information related to the upgrade process and the changes in Zabbix functionality
Informational- all remaining information describing the changes in Zabbix functionality
It is possible to upgrade to Zabbix 4.2.0 from versions before Zabbix 4.0.0. See the upgrade procedure section for all relevant information about upgrading from previous Zabbix versions.
For hosts monitored by proxies, all item (including low-level discovery rules, dependent items) value preprocessing will now be done on the proxy.
It is also no longer possible to use the officially unsupported possibility to start the upgraded server and have older, yet unupgraded proxies report data to a newer server. This approach now is officially disabled when upgrading to 4.2 (or later) from any version before 4.2, as the server will ignore data from unupgraded proxies.
In order to support discovery item value preprocessing and custom paths to low-level discovery (LLD) macro values in a JSON document, the format of the JSON returned by low-level discovery rules has been changed: it is no longer expected that the JSON will contain the "data" object. Instead, low-level discovery will now accept a normal JSON containing an array.
While the "data" element has been removed from all native items related to discovery, for backward compatibility Zabbix will still accept the JSON notation with a "data" element, though its use is discouraged. If the JSON contains an object with only one “data” array element, then it will automatically extract the content of the element using JSONPath
PHP GD library minimum version has been upped from 2.0 to 2.0.28 to support animated GIFs in maps.
Processing low-level discovery has been split from data gathering processes into its own processing. Due to this, depending on how heavy low-level discovery is in your environment, you may:
zabbix[lld_queue] internal item can be used to monitor if the default number of StartLLDProcessors is enough.
Several API features that have been deprecated since Zabbix 3.4, are now completely removed:
httptest.updatemethods: support of string format for 'headers' and 'variables' fields in both web scenario and web scenario step objects has been dropped;
map.updatemethods: support of 'elementid' in map element object has been dropped.
As the global search page has been moved to MVC, its URL has changed from
Host sorting if the 'Host group' map option is selected, is now done non-casesensitively.