8 Known issues

Template nesting issue in Zabbix 6.4.0rc1

Zabbix 6.4.0rc1 (rc1 = Release Candidate 1) does not support template nesting (restored in 6.4.0rc2). If you have upgraded to Zabbix 6.4.0rc1, a DB patch will convert all nested templates into a flat template structure. This means that all entities (items, triggers, etc.) from nested templates will be transferred to the template that contained these nested templates. The support for template nesting has been fully restored in Zabbix 6.4.0rc2. However, if you have already upgraded to Zabbix 6.4.0rc1, the previously existing template structure will not be recovered. :::

Proxy startup with MySQL 8.0.0-8.0.17

zabbix_proxy on MySQL versions 8.0.0-8.0.17 fails with the following “access denied” error:

[Z3001] connection to database 'zabbix' failed: [1227] Access denied; you need (at least one of) the SUPER, SYSTEM_VARIABLES_ADMIN or SESSION_VARIABLES_ADMIN privilege(s) for this operation

That is due to MySQL 8.0.0 starting to enforce special permissions for setting session variables. However, in 8.0.18 this behavior was removed: As of MySQL 8.0.18, setting the session value of this system variable is no longer a restricted operation.

The workaround is based on granting additional privileges to the zabbix user:

For MySQL versions 8.0.14 - 8.0.17:

grant SESSION_VARIABLES_ADMIN on *.* to 'zabbix'@'localhost';

For MySQL versions 8.0.0 - 8.0.13:

grant SYSTEM_VARIABLES_ADMIN on *.* to 'zabbix'@'localhost';

Timescale DB: high memory usage with large number of partitions

PostgreSQL versions 9.6-12 use too much memory when updating tables with a large number of partitions (see problem report). This issue manifests itself when Zabbix updates trends on systems with TimescaleDB if trends are split into relatively small (e.g. 1 day) chunks. This leads to hundreds of chunks present in the trends tables with default housekeeping settings - the condition where PostgreSQL is likely to run out of memory.

The issue has been resolved since Zabbix 5.0.1 for new installations with TimescaleDB, but if TimescaleDB was set up with Zabbix before that, please see ZBX-16347 for the migration notes.

Timescale DB 2.5.0: compression policy can fail on tables that contain integers

This issue manifests when TimescaleDB 2.5.0/2.5.1 is used. It has been resolved since TimescaleDB 2.5.2.

For more information, please see TimescaleDB Issue #3773.

Upgrade with MariaDB 10.2.1 and before

Upgrading Zabbix may fail if database tables were created with MariaDB 10.2.1 and before, because in those versions the default row format is compact. This can be fixed by changing the row format to dynamic (see also ZBX-17690).

Database TLS connection with MariaDB

Database TLS connection is not supported with the ‘verify_ca’ option for the DBTLSConnect parameter if MariaDB is used.

Possible deadlocks with MySQL/MariaDB

When running under high load, and with more than one LLD worker involved, it is possible to run into a deadlock caused by an InnoDB error related to the row-locking strategy (see upstream bug). The error has been fixed in MySQL since 8.0.29, but not in MariaDB. For more details, see ZBX-21506.

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.

Numeric (float) data type range with PostgreSQL 11 and earlier

PostgreSQL 11 and earlier versions only support floating point value range of approximately -1.34E-154 to 1.34E+154.

NetBSD 8.0 and newer

Various Zabbix processes may randomly crash on startup on the NetBSD versions 8.X and 9.X. That is due to the too small default stack size (4MB), which must be increased by running:

ulimit -s 10240

For more information, please see the related problem report: ZBX-18275.

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.

• When using libssh 0.9.x on some Linux distributions with OpenSSH 8, SSH checks may occasionally report “Cannot read data from SSH server”. This is caused by a libssh issue (more detailed report). The error is expected to have been fixed by a stable libssh 0.9.5 release. See also ZBX-17756 for details.

• Using the pipe “|” in the SSH script may lead to a “Cannot read data from SSH server” error. In this case it is recommended to upgrade the libssh library version. See also ZBX-21337 for details.

ODBC checks

• MySQL unixODBC driver should not be used with Zabbix server or Zabbix proxy compiled against MariaDB connector library and vice versa, if possible it is also better to avoid using the same connector as the driver due to an upstream bug. Suggested setup:

  PostgreSQL, SQLite or Oracle connector → MariaDB or MySQL unixODBC driver MariaDB connector → MariaDB unixODBC driver MySQL connector → MySQL unixODBC driver

See ZBX-7665 for more information and available workarounds.

• XML data queried from Microsoft SQL Server may get truncated in various ways on Linux and UNIX systems.

• It has been observed that using ODBC checks for monitoring Oracle databases using various versions of Oracle Instant Client for Linux causes Zabbix server to crash. See also: ZBX-18402, ZBX-20803.

• If using FreeTDS UnixODBC driver, you need to prepend a ‘SET NOCOUNT ON’ statement to an SQL query (for example, SET NOCOUNT ON DECLARE @strsql NVARCHAR(max) SET @strsql = ....). Otherwise, database monitor item in Zabbix will fail to retrieve the information with an error “SQL query returned empty result”.
  See ZBX-19917 for more information.

Incorrect request method parameter in items

The request method parameter, used only in HTTP checks, may be incorrectly set to ‘1’, a non-default value for all items as a result of upgrade from a pre-4.0 Zabbix version. For details on how to fix this situation, see ZBX-19308.

Web monitoring and HTTP agent

Zabbix server leaks memory on some 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

There is a bug in fping versions earlier than v3.10 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.

SNMP data spikes

Spikes in SNMP data have been observed that may be related to certain physical factors like voltage spikes in the mains. See ZBX-14318 more details.

SNMP traps

The “net-snmp-perl” package, needed for SNMP traps, has been removed in RHEL 8.0-8.2; re-added in RHEL 8.3.

So if you are using RHEL 8.0-8.2, the best solution is to upgrade to RHEL 8.3.

Please also see ZBX-17192 for more information.

Alerter process crash in RHEL 7

Instances of a Zabbix server alerter process crash have been encountered in RHEL 7. Please see ZBX-10461 for details.

Compiling Zabbix agent on HP-UX

If you install the PCRE library from a popular HP-UX package site http://hpux.connect.org.uk, for example from file pcre-8.42-ia64_64-11.31.depot, you get only the 64-bit version of the library installed in the /usr/local/lib/hpux64 directory.

In this case, for successful agent compilation customized options need to be used for the “configure” script, e.g.:

CFLAGS="+DD64" ./configure --enable-agent --with-libpcre-include=/usr/local/include --with-libpcre-lib=/usr/local/lib/hpux64

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)

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

Daylight Saving Time

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

Sum aggregation

When using sum aggregation in a graph for period that is less than one hour, graphs display incorrect (multiplied) values when data come from trends.

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.

Slow configuration sync with Oracle

Configuration sync might be slow in Zabbix 6.0 installations with Oracle DB that have high number of items and item preprocessing steps. This is caused by the Oracle database engine speed processing nclob type fields.

To improve performance, you can convert the field types from nclob to nvarchar2 by manually applying the database patch items_nvarchar_prepare.sql. Note that this conversion will reduce the maximum field size limit from 65535 bytes to 4000 bytes for item preprocessing parameters and item parameters such as Description, Script item’s field Script, HTTP agent item’s fields Request body and Headers, Database monitor item’s field SQL query. Queries to determine template names that need to be deleted before applying the patch are provided in the patch as a comment. Alternatively, if MAX_STRING_SIZE is set you can change nvarchar2(4000) to nvarchar2(32767) in the patch queries to set the 32767 bytes field size limit.

For an extended discussion, see ZBX-22363.

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.

Trimmed long IPv6 IP address in failed login information

A failed login attempt message will 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.

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.

YAML export/import

There are some known issues with YAML export/import:

• Error messages are not translatable;
• Valid JSON with a .yaml file extension sometimes cannot be imported;
• Unquoted human-readable dates are automatically converted to Unix timestamps.

Setup wizard on SUSE with NGINX and php-fpm

Frontend setup wizard cannot save configuration file on SUSE with NGINX + php-fpm. This is caused by a setting in /usr/lib/systemd/system/php-fpm.service unit, which prevents Zabbix from writing to /etc. (introduced in PHP 7.4).

There are two workaround options available:

• Set the ProtectSystem option to ‘true’ instead of ‘full’ in the php-fpm systemd unit.
• Manually save /etc/zabbix/web/zabbix.conf.php file.

Chromium for Zabbix web service on Ubuntu 20

Though in most cases, Zabbix web service can run with Chromium, on Ubuntu 20.04 using Chromium causes the following error:

Cannot fetch data: chrome failed to start:cmd_run.go:994:
       WARNING: cannot create user data directory: cannot create 
       "/var/lib/zabbix/snap/chromium/1564": mkdir /var/lib/zabbix: permission denied
       Sorry, home directories outside of /home are not currently supported. See https://forum.snapcraft.io/t/11209 for details.

This error occurs because /var/lib/zabbix is used as a home directory of user ‘zabbix’.

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.

Invalid regular expressions after switching to PCRE2

In Zabbix 6.0 support for PCRE2 has been added. Even though PCRE is still supported, Zabbix installation packages for RHEL 7 and newer, SLES (all versions), Debian 9 and newer, Ubuntu 16.04 and newer have been updated to use PCRE2. While providing many benefits, switching to PCRE2 may cause certain existing PCRE regexp patterns becoming invalid or behaving differently. In particular, this affects the pattern ^[\w-\.]. In order to make this regexp valid again without affecting semantics, change the expression to ^[-\w\.] . This happens due to the fact that PCRE2 treats the dash sign as a delimiter, creating a range inside a character class.

Geomap widget error

The maps in the Geomap widget may not load correctly, if you have upgraded from an older Zabbix version with NGINX and didn’t switch to the new NGINX configuration file during the upgrade.

To fix the issue, you can discard the old configuration file, use the configuration file from the current version package and reconfigure it as described in the download instructions in section e. Configure PHP for Zabbix frontend.

Alternatively, you can manually edit an existing NGINX configuration file (typically, /etc/zabbix/nginx.conf). To do so, open the file and locate the following block:

location ~ /(api\/|conf[^\.]|include|locale|vendor) {
               deny            all;
               return          404;
       }

Then, replace this block with:

location ~ /(api\/|conf[^\.]|include|locale) {
               deny            all;
               return          404;
       }
       location /vendor {
               deny            all;
               return          404;
       }