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# 7 Problèmes connus

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#### Corrélation d’événements

Les événements peuvent ne pas être corrélés correctement si l'intervalle
de temps entre le premier et le deuxième événement est trop petit,
c'est-à-dire une demi-seconde et moins.

[comment]: # ({/b62ae3d3-e338613a})

[comment]: # ({new-2bffe327})
. 
#### Installation from packages

It has been observed that it is impossible to install a specific frontend version 
by running, e.g.:

    yum install -v zabbix-web-mysql-scl-5.0.0

As a workaround to this issue, if you wish to install a specific frontend version, 
specify version for all components, e.g.:

    yum install zabbix-web-mysql-scl-5.0.0 zabbix-apache-conf-scl-5.0.0 zabbix-web-5.0.0 zabbix-web-deps-scl-5.0.0

[comment]: # ({/new-2bffe327})

[comment]: # ({a53a2f15-142de236})
#### Vérifications IPMI

Les vérifications IPMI ne fonctionneront pas avec le paquet de la
bibliothèque standard OpenIPMI sur Debian avant 9 (stretch) et Ubuntu
avant 16.04 (xenial). Pour résoudre ce problème, recompilez la
bibliothèque OpenIPMI avec OpenSSL activé comme indiqué dans
[ZBX-6139](https://support.zabbix.com/browse/ZBX-6139).

[comment]: # ({/a53a2f15-142de236})

[comment]: # ({1578b452-68c1ee03})
#### Vérifications SSH

Certaines distributions Linux comme Debian et Ubuntu ne supportent pas
les clés privées cryptées (avec phrase secrète) si la bibliothèque
libssh2 est installée à partir des packages. Voir
[ZBX-4850](https://support.zabbix.com/browse/ZBX-4850) pour plus de
détails.

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#### Vérifications ODBC

Le serveur Zabbix ou le proxy qui utilise MySQL comme base de données
peut ou ne peut pas fonctionner correctement avec la bibliothèque MySQL
ODBC en raison d'un [bug en
amont](https://bugs.mysql.com/bug.php?id=73709). Voir
[ZBX-7665](https://support.zabbix.com/browse/ZBX-7665) pour plus
d'informations et les solutions de contournement disponibles.

Les données XML interrogées à partir de Microsoft SQL Server peuvent
être tronquées à 2033 caractères en raison d'un
[problème](https://support.microsoft.com/en-us/help/310378/the-xml-data-row-is-truncated-at-2-033-characters-when-you-use-the-sql)
Microsoft.

[comment]: # ({/11108657-fd4031a0})

[comment]: # ({05a04b08-40e33d04})
#### Vérifications HTTPS

Les scénarios Web utilisant le protocole https et les vérifications
d'agent Zabbix `net.tcp.service[https…]` et
`net.tcp.service.perf[https…]` peuvent échouer si le serveur cible est
configuré pour interdire le protocole TLS v1.0 ou inférieur. Voir
[ZBX-9879](https://support.zabbix.com/browse/ZBX-9879) pour plus
d'informations et les solutions de contournement disponibles.

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#### 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](https://github.com/mysql/mysql-server/commit/7037a0bdc83196755a3bf3e935cfb3c0127715d5)). 
The error has been fixed in MySQL since 8.0.29, but not in MariaDB. For more details, see [ZBX-21506](https://support.zabbix.com/browse/ZBX-21506).

[comment]: # ({/new-eb4d0f92})

[comment]: # ({4713dff4-70c19e71})
#### 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](https://bugzilla.redhat.com/show_bug.cgi?id=1057388) when "SSL
verify peer" is enabled in web scenarios or HTTP agent. Please see
[ZBX-10486](https://support.zabbix.com/browse/ZBX-10486) for more
information and available workarounds.

[comment]: # ({/4713dff4-70c19e71})

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#### Vérifications Simples

Un bug existe dans les versions de **fping** antérieures à la version
v3.10 release 2.1.2 qui traite mal les paquets echo replay dupliqués.
Cela peut provoquer des résultats inattendus pour les éléments
`icmpping`, `icmppingloss`, `icmppingsec`. Il est recommandé d'utiliser
la dernière version de **fping**. Voir
[ZBX-11726](https://support.zabbix.com/browse/ZBX-11726) pour plus de
détails.

[comment]: # ({/4d4ea281-215c95a7})

[comment]: # ({0619d325-dfc40df7})
#### Vérifications SNMP

Si le système d'exploitation OpenBSD est utilisé, un bug dans la
bibliothèque Net-SNMP jusqu'à la version 5.7.3 peut provoquer un
plantage du serveur Zabbix si le paramètre SourceIP est défini dans le
fichier de configuration du serveur Zabbix. Pour contourner le problème,
ne définissez pas le paramètre SourceIP. Le même problème s'applique
également à Linux, mais cela n'empêche pas le serveur Zabbix de
fonctionner. Un correctif local pour le package net-snmp sur OpenBSD a
été appliqué et sera publié avec OpenBSD 6.3.

[comment]: # ({/0619d325-dfc40df7})

[comment]: # ({d0eb9c2f-3cf04fe3})
#### Problème de compatibilité avec PHP 7.0

Il a été observé qu'avec PHP 7.0, l'importation d'un modèle avec des
déclencheurs de surveillance Web peut échouer en raison de l'ajout
incorrect de doubles guillemets aux éléments de surveillance Web dans
les expressions de déclencheur. Le problème disparaît lors de la mise à
jour de PHP vers la version 7.1.

[comment]: # ({/d0eb9c2f-3cf04fe3})

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#### Graphiques

Les modifications apportées à l'heure d'été (DST) entraînent des
irrégularités lors de l'affichage des libellés de l'axe X (duplicat de
date, date manquante, etc.).

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#### Supervision de fichier journaux

Les éléments `log[]` et `logrt[]` relisent de manière répétée le fichier
de logs depuis le début si le système de fichiers est plein à 100% et
que de nouvelles entrées sont ajoutées au fichier journal (voir
[ZBX-10884](https://support.zabbix.com/browse/ZBX-10884) pour plus
d'informations).

[comment]: # ({/bf5e2b62-0c2fc2b9})

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#### Requêtes MySQL lentes

Le serveur Zabbix génère des requêtes SELECT lentes en cas de valeurs
non existantes pour les éléments. Ceci est dû à un
[problème](https://bugs.mysql.com/bug.php?id=74602) connu dans les
versions MySQL 5.6/5.7. Une solution de contournement consiste à
désactiver l'optimiseur index\_condition\_pushdown dans MySQL. Pour une
discussion approfondie, voir
[ZBX-10652](https://support.zabbix.com/browse/ZBX-10652).

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#### Accès API

Un grand nombre de sessions utilisateur ouvertes peuvent être créées
lors de l'utilisation de scripts personnalisés avec la
[méthode](/manual/api/reference/user/login) `user.login` sans la
présence du paramètre `user.logout` ensuite.

[comment]: # ({/2036de7d-4713dff4})

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#### 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](https://support.zabbix.com/browse/ZBX-11726) for more
details.

[comment]: # ({/9cd7efe1-9cd7efe1})

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#### Errors with fping execution in rootless containers

When containers are running in rootless mode or in a specific-restrictions environment, you may face errors related to fping execution when performing ICMP checks, such as `fping: Operation not permitted` or all packets to all resources lost. 

To fix this problem add `--cap-add=net_raw` to "docker run" or "podman run" commands. 

Additionally fping execution in non-root environments may require sysctl modification, i.e.: 

    sudo sysctl -w "net.ipv4.ping_group_range=0 1995"

where "1995" is the zabbix GID. For more details, see [ZBX-22833](https://support.zabbix.com/browse/ZBX-22833).

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#### 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.

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#### 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](https://support.zabbix.com/browse/ZBX-14318) more details.

[comment]: # ({/d699f9d6-d699f9d6})

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#### SNMP traps

The "net-snmp-perl" package, needed for SNMP traps, has been removed in
RHEL/CentOS 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; if you are using CentOS 8.0-8.2, you may wait for CentOS 8.3
or use a package from EPEL.

Please also see [ZBX-17192](https://support.zabbix.com/browse/ZBX-17192)
for more information.

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[comment]: # ({f46cb486-f46cb486})
#### Alerter process crash in Centos/RHEL 7

Instances of a Zabbix server alerter process crash have been encountered
in Centos/RHEL 7. Please see
[ZBX-10461](https://support.zabbix.com/browse/ZBX-10461) for details.

[comment]: # ({/f46cb486-f46cb486})


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#### 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](https://www.php.net/manual/en/function.setlocale): 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](https://support.zabbix.com/browse/ZBX-10911) (Problem
    with flipping frontend locales)
-   [ZBX-16297](https://support.zabbix.com/browse/ZBX-16297) (Problem
    with number processing in graphs using the `bcdiv` function of BC
    Math functions)

[comment]: # ({/6e1fb8fe-6e1fb8fe})

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#### 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](https://bugs.php.net/bug.php?id=78015). To work
around this, please set the "opcache.optimization\_level" parameter to
`0x7FFFBFDF` in the PHP configuration (php.ini file).

[comment]: # ({/81fe18ae-81fe18ae})

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#### Graphs

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

[comment]: # ({/4f3b73ce-4f3b73ce})

[comment]: # ({357fdb5b-357fdb5b})
#### 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](https://support.zabbix.com/browse/ZBX-10884) for more
information).

[comment]: # ({/357fdb5b-357fdb5b})

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#### Slow MySQL queries

Zabbix server generates slow select queries in case of non-existing
values for items. This is caused by a known
[issue](https://bugs.mysql.com/bug.php?id=74602) 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](https://support.zabbix.com/browse/ZBX-10652).

[comment]: # ({/82ff58c2-82ff58c2})

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##### Permission checks for dashboards with graphs
If SVG graphs are used in Zabbix dashboards, Zabbix frontend may generate non-optimized API queries when checking user permissions to hosts and items. 
This is happening because such searches support wildcards and case-insensitive name matching. 

To improve performance of SQL statements, manually apply the patch *index_host_and_item_name_upper_field.sql* provided in Zabbix 5.0.31 and newer. 

For MySQL, run:

    shell> mysql -uzabbix -p<password> zabbix < index_host_and_item_name_upper_field.sql

For PostgreSQL, run:

    shell> cat index_host_and_item_name_upper_field.sql | sudo -u zabbix psql zabbix

For Oracle, run:
    
    sqlplus> @index_host_and_item_name_upper_field.sql

Creation of deterministic triggers should be enabled for the time of patch application. 
On MySQL and MariaDB, this requires `GLOBAL log_bin_trust_function_creators = 1` to be set 
if binary logging is enabled and there is no superuser privileges and `log_bin_trust_function_creators = 1` is not set in MySQL configuration file. 
To set the variable using MySQL console, run:

    mysql> SET GLOBAL log_bin_trust_function_creators = 1;

Once the patch has been successfully applied, `log_bin_trust_function_creators` can be disabled:

    mysql> SET GLOBAL log_bin_trust_function_creators = 0;

Triggers are also created for PostgreSQL and Oracle database.

[comment]: # ({/new-96b24508})

[comment]: # ({new-1fb1a6a2})

##### Non-existing item value retrieval with MySQL 5.6/5.7
Zabbix server generates slow select queries in case of non-existing
values for items. This is caused by a known
[issue](https://bugs.mysql.com/bug.php?id=74602) 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](https://support.zabbix.com/browse/ZBX-10652).

[comment]: # ({/new-1fb1a6a2})

[comment]: # ({new-184e8f10})
##### Slow event info retrieval with older MySQL databases

Zabbix 5.0 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](https://support.zabbix.com/browse/ZBX-18080?focusedCommentId=477904&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-477904)
(available for Zabbix 5.0.4 and newer).

[comment]: # ({/new-184e8f10})

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#### API login

A large number of open user sessions can be created when using custom
scripts with the `user.login` [method](/manual/api/reference/user/login)
without a following `user.logout`.

[comment]: # ({/b393528e-b393528e})

[comment]: # ({17c4463f-17c4463f})
#### 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](https://support.zabbix.com/browse/ZBX-14541).

[comment]: # ({/17c4463f-17c4463f})

[comment]: # ({430b9c2e-430b9c2e})
#### Trimmed long IPv6 IP address in failed login information

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.

[comment]: # ({/430b9c2e-430b9c2e})

[comment]: # ({57420738-57420738})
#### 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.

[comment]: # ({/57420738-57420738})

[comment]: # ({fcbf4bce-fcbf4bce})
#### 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](https://bugs.php.net/bug.php?id=72510)).

There are two workaround options available:

-   Set the
    [ProtectSystem](https://www.freedesktop.org/software/systemd/man/systemd.exec.html#ProtectSystem=)
    option to 'true' instead of 'full' in the php-fpm systemd unit.
-   Manually save /etc/zabbix/web/zabbix.conf.php file.

[comment]: # ({/fcbf4bce-fcbf4bce})

[comment]: # ({1f99c5d8-1f99c5d8})
#### 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.

[comment]: # ({/1f99c5d8-1f99c5d8})