Release Notes for Zabbix 4.0.21rc1

Zabbix Team is pleased to announce the availability of Zabbix 4.0.21rc1.

Zabbix is an enterprise-class open source distributed monitoring solution. Zabbix is released under the GPL, thus it is free of charge for both commercial and non-commercial use. A complete text of the license is available at

This document contains the release notes for Zabbix 4.0.21rc1. Download it from download.

The following sections describe the release in details and provide late-breaking or other information that supplements its main documentation.

New Features and Improvements

ZBXNEXT-5922 Increased max configuration cache size limit to 64GB

Bug Fixes

ZBX-17662 Fixed a failing query when updating existing host prototypes
ZBX-15484 Shadow global auto_increment variables for MySQL
ZBX-17607 Fixed unreachable poller being too busy due to SNMP checks being attempted twice at a time
ZBX-17629 Fixed markup in User Media popup
ZBX-17109 Fixed agent request parameter type parsing
ZBX-17470 Fixed element of filters is not focused on several pages
ZBX-17691 Fixed server crashes on regexp preprocessing
ZBX-17445 Fixed misleading error shown when formula cannot be updated during LLD
ZBX-17186 Fixed context-aware LLD macro expansion in JsonPath preprocessing

Installation and Upgrade Notes


See Zabbix Manual for full details.


Recompile Zabbix binaries and update front-end PHP files. Execute a database patch if migrating from Zabbix 1.8.x. See Zabbix manual for a detailed upgrade procedure.

Commercial support

Zabbix Company provides a full range of Professional Services. We also provide trouble-free Upgrade Service for easy migration from earlier versions of Zabbix. Please Contact sales for pricing and more details.


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