7 Known issues

Global event correlation

Events may not get correlated correctly if the time interval between the first and second event is very small, i.e. half a second and less.

IPMI checks

IPMI checks will not work with the standard OpenIPMI library package on Debian prior to 9 (stretch) and Ubuntu prior to 16.04 (xenial). To fix that, recompile OpenIPMI library with OpenSSL enabled as discussed in ZBX-6139.

SSH checks

Some Linux distributions like Debian, Ubuntu do not support encrypted private keys (with passphrase) if the libssh2 library is installed from packages. Please see ZBX-4850 for more details.

ODBC checks

Zabbix server or proxy that uses MySQL as its database may or may not work correctly with MySQL ODBC library due to an upstream bug. Please see ZBX-7665 for more information and available workarounds.

XML data queried from Microsoft SQL Server may get truncated to 2033 characters due to a Microsoft issue.

HTTPS checks

Web scenarios and HTTP agent items using the https protocol, Zabbix agent checks net.tcp.service[https...] and net.tcp.service.perf[https...] may fail if the target server is configured to disallow TLS v1.0 protocol or below. Please see ZBX-9879 for more information and available workarounds.

Web monitoring and HTTP agent

Zabbix server leaks memory on CentOS 6, CentOS 7 and possibly other related Linux distributions due to an upstream bug when "SSL verify peer" is enabled in web scenarios or HTTP agent. Please see ZBX-10486 for more information and available workarounds.

Simple checks

A bug exists in fping versions earlier than v3.10 release 2.1.2 that mishandles duplicate echo replay packets. This may cause unexpected results for icmpping, icmppingloss, icmppingsec items. It is recommended to use the latest version of fping. Please see ZBX-11726 for more details.

SNMP checks

If the OpenBSD operating system is used, a use-after-free bug in the Net-SNMP library up to the 5.7.3 version can cause a crash of Zabbix server if the SourceIP parameter is set in the Zabbix server configuration file. As a workaround, please do not set the SourceIP parameter. The same problem applies also for Linux, but it does not cause Zabbix server to stop working. A local patch for the net-snmp package on OpenBSD was applied and will be released with OpenBSD 6.3.

Graphs

Changes to Daylight Saving Time (DST) result in irregularities when displaying X axis labels (date duplication, date missing, etc).

Log file monitoring

log[] and logrt[] items repeatedly reread log file from the beginning if file system is 100% full and the log file is being appended (see ZBX-10884 for more information).

Slow MySQL queries

Zabbix server generates slow select queries in case of non-existing values for items. This is caused by a known issue in MySQL 5.6/5.7 versions. A workaround to this is disabling the index_condition_pushdown optimizer in MySQL. For an extended discussion, see ZBX-10652.

API

The output parameter does not work properly with the history.get method.

API login

A large number of open user sessions can be created when using custom scripts with the user.login method without a following user.logout.

IPv6 address issue in SNMPv3 traps

Due to a net-snmp bug, IPv6 address may not be correctly displayed when using SNMPv3 in SNMP traps. For more details and a possible workaround, see ZBX-14541.

Known issues for 4.0.0

• Fullscreen mode for the dashboards cannot be accessed with the respective URL parameter: /zabbix.php?action=dashboard.view&fullscreen=1. Fixed in 4.0.1.
• When filtering triggers in Monitoring → Overview (Triggers), trigger severity instead of problem severity is taken into account.

Flipping frontend locales

It has been observed that frontend locales may flip without apparent logic, i. e. some pages (or parts of pages) are displayed in one language while other pages (or parts of pages) in a different language. Typically the problem may appear when there are several users, some of whom use one locale, while others use another.

A known workaround to this is to disable multithreading in PHP and Apache.

The problem is related to how setting the locale works in PHP: locale information is maintained per process, not per thread. So in a multi-thread environment, when there are several projects run by same Apache process, it is possible that the locale gets changed in another thread and that changes how data can be processed in the Zabbix thread.

For more information, please see related problem reports:

• ZBX-10911 (Problem with flipping frontend locales)
• ZBX-16297 (Problem with number processing in graphs using the bcdiv function of BC Math functions)

Compatibility issue with PHP 7.0

It has been observed that with PHP 7.0 importing a template with web monitoring triggers may fail due to incorrectly added double quotes to the web monitoring items in the trigger expressions. The issue goes away when upgrading PHP to 7.1.

PHP 7.3 opcache configuration

If "opcache" is enabled in the PHP 7.3 configuration, Zabbix frontend may show a blank screen when loaded for the first time. This is a registered PHP bug. To work around this, please set the "opcache.optimization_level" parameter to 0x7FFFBFDF in the PHP configuration (php.ini file).

Graphs

Changes to Daylight Saving Time (DST) result in irregularities when displaying X axis labels (date duplication, date missing, etc).

Log file monitoring

log[] and logrt[] items repeatedly reread log file from the beginning if file system is 100% full and the log file is being appended (see ZBX-10884 for more information).

Slow MySQL queries

Zabbix server generates slow select queries in case of non-existing values for items. This is caused by a known issue in MySQL 5.6/5.7 versions. A workaround to this is disabling the index_condition_pushdown optimizer in MySQL. For an extended discussion, see ZBX-10652.

MariaDB row size error

Prior to MariaDB 10.2.26, 10.3.17, and 10.4.7, MariaDB didn't properly calculate the row sizes while executing DDL, so "unsafe" tables could be created, even with innodb_strict_mode=ON set. This was fixed by MDEV-19292. As a side effect, tables that could be created in previous versions may get rejected after the latest releases.

Suggested database changes for existing 4.0 installations:

shell> mysql -uroot -p<password>
       mysql> alter table `host_inventory` modify `name` varchar(128) default '' not null, modify `alias` varchar(128) default '' not null, modify `os` varchar(128) default '' not null, modify `os_short`   varchar(128) default '' not null;

Suggested database changes for new 4.0 installations:

shell> mysql -uroot -p<password>
       mysql> set global innodb_strict_mode='OFF';

Perform database creation as usual and fix schema after:

shell> mysql -uroot -p<password>
       mysql> alter table `host_inventory` modify `name` varchar(128) default '' not null, modify `alias` varchar(128) default '' not null, modify `os` varchar(128) default '' not null, modify `os_short` varchar(128) default '' not null;
       mysql> set global innodb_strict_mode='ON';

API

The output parameter does not work properly with the history.get method (fixed in 4.0.11).

API login

A large number of open user sessions can be created when using custom scripts with the user.login method without a following user.logout.

IPv6 address issue in SNMPv3 traps

Due to a net-snmp bug, IPv6 address may not be correctly displayed when using SNMPv3 in SNMP traps. For more details and a possible workaround, see ZBX-14541.

IE11 issue with map resizing in dashboard widgets

Maps, in Internet Explorer 11, are cut off on the right side if the map content is larger than the dashboard widget area (instead of being resized proportionately). This is intentional because of an IE11-related issue with proper resizing of SVG images.

Zabbix agent checks on Windows

Non-existing DNS entries in a Server parameter of Zabbix agent configuration file (zabbix_agentd.conf) may increase Zabbix agent response time on Windows. This happens because Windows DNS caching daemon doesn't cache negative responses for IPv4 addresses. However, for IPv6 addresses negative responses are cached, so a possible workaround to this is disabling IPv4 on the host.

MySQL custom error codes

If Zabbix is used with MySQL installation on Azure, an unclear error message [9002] Some errors occurred may appear in Zabbix logs. This generic error text is sent to Zabbix server or proxy by the database. To get more information about the cause of the error, check Azure logs.

Known issues in 4.0.0

• Fullscreen mode for the dashboards cannot be accessed with the respective URL parameter: /zabbix.php?action=dashboard.view&fullscreen=1. Fixed in 4.0.1.
• When filtering triggers in Monitoring → Overview (Triggers), trigger severity instead of problem severity is taken into account.

Known issues in 4.0.0, 4.0.1

• Upgrade to 4.0.0 and 4.0.1 from Zabbix 3.0 does not replace {TRIGGER.NAME} macros to {EVENT.NAME} macros like it should. Fixed for 4.0.2.

Known issues in 4.0.0 - 4.0.2

• If the Check now request is performed from the item list for items that do not support it (template items, active agent items, etc.), a 'Request sent successfully' message is displayed even though the functionality does not work for these items. Fixed in 4.0.3, by displaying a corresponding error message.

Known issues in 4.0.2

• Parent host group selection does not work in the following locations:
  • Monitoring → Problems filter
  • Monitoring → Dashboard widgets with host group selection:
  • Reports → Triggers top 100 filter

Known issues in 4.0.0 - 4.0.3

• Time suffixes do not work in constants of calculated item formulas. Fixed in 4.0.4.
• Negative problem duration affects the total result in SLA calculation or Availability report, making it incorrect. Fixed in 4.0.4.

Known issues in 4.0.3

• If an item is deleted that has a low-level discovery created trigger, the trigger is not deleted. This leads to "orphaned" problems (with no item/host) being displayed in the problem view. Similarly, if an item is deleted that has low-level discovery created dependent item, the dependent item is not deleted. Fixed in 4.0.4.

Known issues starting with 4.0.3

• Failed login attempt message has been changed to display only the first 39 characters of a stored IP address as that's the character limit in the database field. That means that IPv6 IP addresses longer than 39 characters will be shown incompletely.

Known issues in 4.0.0 - 4.0.5

• net.dns[] Zabbix agent item does not support IPv6 addresses in its first parameter. Fixed in 4.0.6.

Slow event info retrieval with older MySQL databases

Zabbix 4.0 installations with MySQL 5.X and 8.0.19 might run a slow query when retrieving problem/event information from the database. In particular, this affects the Problems by severity widget, event.get and problem.get API methods. To improve performance of SQL statements, apply the patch provided in ZBX-18080 (available for Zabbix 4.0.26 and newer).

Known issues in 4.0.6, 4.0.7

• IPMI pollers are unable to process more than 60 items per minute. Fixed in 4.0.8.
• You may encounter the issue of 100% CPU usage by IPMI pollers if using OpenIPMI version 2.0.26 and above. Fixed in 4.0.8.

Known issues in 4.0.8

• This version requires write permissions to the assets directory for the web server user. This requirement, however, would break those installations of the frontend where the web server has no write permissions to the document root (see ZBX-16180 for details). As a result, this requirement is rolled back in 4.0.9.

Known issues in 4.0.0 - 4.0.15

• High memory usage has been observed during process startup with SQLite 3.7.17 on Centos/RHEL 7. The startup process has been improved in 4.0.16 to avoid similar issues with other databases as well. See ZBX-9084 for more details.