Overview This KB article explains how you can troubleshoot Active Directory (AD) and Lightweight Directory Access Protocol (LDAP) authentication issues. The troubleshooting methods are similar across Nagios Log Server, Network Analyzer and XI... Read More

In Nagios XI versions prior to 5.7, there was an API issue as described below: The JSON returned from the API returns inconsistent types depending on whether single or multiple results are returned. As an example, requesting the status of a single... Read More

If you are running Nagios XI 5.6.11, most likely your backups won't be compressed. You can verify if this is the case by listing the contents of the backup directory: ls -la /store/backups/nagiosxi If you see any directories, that are NOT... Read More

Problem Description The Core Config Manager in Nagios XI is saying that there are unapplied changes, but none of the listed objects are marked as modified.     Resolving The Problem Performing an Apply Config should resolve the issue.    ... Read More

How to disable outdated versions of SSL/TLS in Apache   In order to provide the most robust security possible, old versions of SSL/TLS should be disabled. Most modern browsers support the newer and more secure versions of SSL/TLS so disabling the... Read More

Problem Description You are seeing port 113 return requests either from your Nagios XI server (when submitting NSCA passive results) to the originating host OR you are seeing port 113 return requests when checking NRPE services). You will see this... Read More

Problem Description When you attempt to install or upgrade one of the Nagios products you receive the following error: ERROR: Please enable the 'Optional' repo for your system in:   Resolving The Problem You need to add the Optional... Read More

Problem Description When you attempt to install or upgrade Nagios XI you receive the following error: "ERROR: Please add the 'Optional' channel to your Red Hat systems subscriptions   Resolving The Problem Red Hat Subscription Manager: You... Read More

Overview In larger enterprises, a "standard build" of CentOS or RHEL is required based on internal policies. These often differ from a clean minimal install of the OS as per our requirements. Depending on the policies implemented in the build process... Read More

Problem Description This KB article addresses the following errors you may see in the nagios.log file: [1504231962] wproc: Core Worker 68003: Failed to register iobroker for stdout[1504231962] wproc: Core Worker 68003: Failed to register iobroker for... Read More

Problem Description In larger deployments of nagios, stopping or restarting the nagios service may result in the error: Nagios did not exit in a timely manner This is due to many factors in large deployments, but basically it is just a timeout issue.... Read More

Problem Description Bandwidth graphs in Nagios XI are showing no bandwidth. When manually executing MRTG you see the following output: MRTG Manual Command: LANG=C LC_ALL=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg This error is produced: ERROR: unable to open... Read More

Overview The most common error experienced during the XI 2014 upgrade process is the following core config error: CONFIG ERROR! Restart aborted. Check your Nagios configuration.   XI 2014 introduced some new mechanisms to guard against and remove... Read More

Problem Description Nagios XI 2012 and late versions of 2011 set up apache to be able to utilize the Ajaxterm subcomponent. This component requires a modification to the /etc/httpd/conf.d/ssl.conf file, and adds some proxy information needed... Read More

Problem Description Apply Configuration fails with the following error: Backend login to the Core Config Manager failed.An error occurred while attempting to apply your configuration to Nagios Core.Monitoring engine configuration files have been... Read More

Problem Description If you attempt to Apply Configuration and you're seeing the following output: The following error message is produced: * Configuration submitted for processing...* Waiting for configuration verification.................. The... Read More

Problem Description When running Nagios XI on a system which uses certain non-English languages, bandwidth services (amongst others) and their associated graphs may incorrectly report 0 Mb/s even though there is traffic actively flowing through the... Read More

Best Practices - NWC15 Best Practices? That’s like asking how long is a piece of string! While every environment is different, there are however a number of configurations, tweaks and methods that can be of great benefit for your Nagios XI... Read More

Problem Description Sometimes a user can connect to the Nagios XI server via ssh (putty) session but he/she is not able to log in to the web UI.     Possible Causes There could be various reasons for this problem. Here are some of the possible... Read More

Problem Description Between the the release of Nagios XI 2011R1.7 and 1.8, several changes were made to the CentOS 6 repo that created package conflicts, preventing the Nagios XI installation scripts from completing successfully. This usually becomes... Read More

Overview This KB article covers some of the more common problems that can occur when upgrading Nagios XI and provides solutions to them.   Upgrade Instructions And Methods Steps for performing the upgrades themselves can be found at: Nagios XI -... Read More

Problem Description The applying configuration completes successfully and the changes are visible in the XI interface, but you're still seeing an error message in the CCM that says "Configuration File Is Out Of Date".   Resolving The Problem... Read More

Overview This is generally due to wrong permissions or issues with the sudoers settings. In order to reset the permissions, run the following command from the command line: /usr/local/nagiosxi/scripts/reset_config_perms.sh   If running the above... Read More

Problem Description In Core Configuration Manager (CCM) when you Apply Configuration you receive the error message Configuration verification failed :     When you click the Show Errors link a message is shown that indicates the... Read More

Problem Description With the release of Nagios XI 2014 the core version on the back-end was updated to Core 4. This introduced a issue in certain environments where an extremely high system level load can occur at intervals most commonly between an... Read More

Problem Description When using Core Configuration Manager (CCM), the interface does not work as expected, it does not appear to display correctly and generally it feels like there is a bug.   Explanation Most of these are related to the web browsers... Read More

Crashed Database Tables If you experience high load on your Nagios XI server and the MySQL process (mysqld) appears to be consuming large amounts of CPU, it may be a symptom of one or more crashed tables. In order to find out if you have crashed... Read More

Overview This article covers troubleshooting bandwidth performance graphs when they are not appearing as expected. This can include: No graphs at all Gaps of no data in the performance graphs   Common causes are: Cron daemon is not running ... Read More

Problem Description When setting up a check in Nagios, you may get a error similar to the following: [Can't locate Monitoring/Plugin.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share... Read More

Overview This document describes how to disable UTF8 connectivity to the MySQL / MariaDB databases for Nagios XI. By default Nagios XI uses UTF8 however sometimes this needs to be disabled to allow MySQL / MariaDB to define the connectivity method.... Read More

Overview The reporting functionality in Nagios XI is implemented "per user", each individual user can create their own scheduled reports. Currently there is no centralized view of all scheduled reports by all users in Nagios XI. However there are... Read More

Downloading A System Profile In Nagios XI This video will demonstrate how to view and download a system profile in Nagios XI for the purposes of troubleshooting.         Final Thoughts For any support related questions please visit the Nagios... Read More

Problem Description In some pages of XI you may come across empty screens, such as no configuration wizards appearing under the Configure menu.   Explanation When plugins, components or wizards are not installed through the proper menus, this... Read More

Problem Description In Nagios XI, when saving a performance graph as a PNG, JPEG image you receive the following error: Error while converting SVG   You may also see the following error logged in /var/log/httpd/error_log: sh: ./phantomjs: /lib/ld... Read More

Problem Description This anomaly will rarely occur during a VM set up of Nagios XI. The following is an example of what it may look like: cp: cannot create regular file `/usr/local/nagiosxi/scripts':  Read-only file systemcp: cannot create... Read More

Problem Description Bandwidth graphs in Nagios XI are showing no bandwidth. When manually executing MRTG you see the following output: MRTG Manual Command: LANG=C LC_ALL=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg This error is produced: ERROR: unable to open... Read More

Problem Description There is a known bug relating to event data in versions 2009R1.4B-2011R1.1. This bug has been patched and will be available in releases later than the versions posted above, but if you're experiencing this error, and/or the... Read More

Host Still Visible After Deletion (Ghost Hosts) You have successfully deleted a host and all of it's services from the Core Config Manager, but you are still seeing it the web UI.     Possible Causes It is possible that you have multiple... Read More

Problem Description Your host objects (or services) are in a Pending state and they appear gray in color.   Explanation This problem can occur when the host or service object does not have a check command assigned to it.   Resolving The Problem Add... Read More

Overview This KB article explains how to remove a data source from an RRD file. This article applies if you are seeing similar entries in the log file /usr/local/nagios/var/perfdata.log after enabling debug logging in /usr/local/nagios/etc/pnp... Read More

Overview This guide explains how to test check commands from command line in Nagios XI. While there is the Test Check Command button in Core Configuration Manager (CCM), this does not always work as expected due to: PHP character escaping for... Read More

Overview This KB article shows you how to use certificate authority (CA) certificates with the check_ldaps plugin.   Problem When you try and execute the check_ldaps plugin: /usr/local/nagios/libexec/check_ldaps -H dc01.domain.local -b ''... Read More

Problem Description For those doing manual installations, some of the tools embedded in Nagios XI use the PHP short tags feature, which is not necessarily enabled on all web servers by default. This results in the errors "HTTP 500 Error"/"PHP Parse... Read More

Problem Description After upgrading to Nagios XI 5.x, when you login you are presented with a white screen or a 500 error.   Resolving The Problem In Nagios XI 5, a new LDAP component was added and is intended to replace the original Active... Read More

Problem Description Due to issues with rrdtool and the performance graphs, rrdtool may cease to record performance data to RRDs from check_icmp. This is caused by the addition of new performance datasources returned from the check_icmp plugin in... Read More

Overview This KB article explains how to install the latest SourceGuardian loaders that Nagios XI uses with PHP.   Install Establish a terminal session to your Nagios XI server as the root user and execute the following commands: cd /tmprm -rf... Read More

Problem Description When trying to install Nagios XI it fails with the following error: --> Processing Dependency: pymssql for package: nagiosxi-deps-2012r2.9-1.noarch--> Finished Dependency ResolutionError: Package: nagiosxi-deps-2012r2.9-1... Read More

Problem Description Early implementations of Mod-Gearman in XI 2014 had some issues with the new line "\n" character and performance data. This has been resolved however the fixes used are documented here.   Resolving The Problem You will need... Read More

Summary There are many causes for this error. Most often it is due to a connection issue to the backend historical database, crashed database tables, core scheduling/check execution issues, or lack of resources (causing orphaned checks).    ... Read More

Problem Description The web browser keeps redirecting to the login screen even after entering login credentials. This has been noticed in Internet Explorer.   Explanation Nagios XI uses cookies to save session state. These cookies are set to expire... Read More

Overview Historical performance data that is used to generate graphs are stored in Round Robin Database (RRD) files. RRD performance data files are compiled binaries, so for a simple file transfer a user would have to have the architecture match on... Read More

Missing localhost alerts? Here's why. Pro Tip: Make sure you don't overlook this localhost setting.         Final Thoughts For any support related questions please visit the Nagios Support Forums at: http://support.nagios.com/forum/ Read More

Problem Description It has been observed that when you use the combination of Nagios Core 4 + Mod-Gearman + MK Livestatus, nagios can segfault on passive check results. The issue is with MK Livestatus used in this combination. The following... Read More

Problem Description You manually make changes to the configuration files located in /usr/local/nagios/etc/ however you later find that after applying configuration in Core Configuration Manager (CCM) these changes are lost.   Explanation Nagios XI... Read More

Problem Description When running MRTG at the command line: LANG=C LC_ALL=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg --lock-file /var/lock/mrtg/mrtg_l --confcache-file /var/lib/mrtg/mrtg.ok   You receive errors similar to this: Subroutine SNMP_Session:... Read More

Problem Description After running the MSSQL Query wizard your new service has an UNKNOWN state with the following error: UNKNOWN: Invalid characters in the username.   This problem can occur when trying to connect using Windows authentication and... Read More

Problem Description After running the MSSQL wizards your new service has a CRITICAL or UNKNOWN state with the following error: CRITICAL: Could not connect to dblib:host=mssql01.box293.local:1433;dbname=Sample as BOX293nagios(Exception: SQLSTATE[01002... Read More

Overview This KB article is about the MySQL / MariaDB database and adjusting the maximum connections allowed. This can be required in larger XI installations. Historically MySQL has been the database used by Nagios XI, however in CentOS 7 &... Read More

Overview This KB article explains how to resolve the following errors that appear in the /var/log/messages file on your Nagios XI server: Aug 14 23:30:03 centosxx ndo2db: Error: mysql_query() failed for 'INSERT INTO nagios_scheduleddowntime SET... Read More

Nagios XI - Notification Problems Email Tests Send a test email to see if the Nagios server can send email to an account by going to: Configure->My Account Settings->Send Test Notifications. Then, check to see if the test email arrives. If it... Read More

Problem Description After upgrading to Nagios XI 5.3.0 you no longer receive any notifications. The initial release of Nagios XI 5.3.0 had an incorrect file that is the source of the problem.     Solution As of 9am UTC October 4th an updated 5.3.0... Read More

Overview Session protection was added to 2009R1.2C to prevent CSRF attacks. This code to do this caused some users to see this error. The problem was due to the user's browser caching older versions of the XI javascript code. In order to clear... Read More

Overview This KB article provides steps on optimizing the PHP settings file php.ini on your Nagios XI server. There are certain situations where the default settings in PHP need increasing to improve the features of Nagios XI on larger systems. PHP... Read More

Problem Description After upgrading Nagios XI, Oracle based services start failing with errors similar to this: The following error message is produced: CRITICAL - cannot connect to fprnt. install_driver(Oracle) failed: Can't load '/usr... Read More

Problem Description Performance graphs not displaying data when their checks are returning true performance data. The following troubleshooting steps may help you to find the root cause of the issue, and resolve it.     Editing Files In many steps... Read More

Overview We do not officially support Nagios XI when you install and use proxy software that restricts traffic to or from the Nagios XI server. There are several reasons for this. First, Nagios XI requires external access for package installation and... Read More

Problem Description Certain services in Microsoft Windows use special characters in the service name like MSSQLFDLauncher$UWCX01. This causes problems with Nagios as it thinks the $ is part of a variable.     Resolving The Problem Using NCPA Your... Read More

Problem Description When you go to Admin > System Config > System Profile and try to download the profile you receive the following error: PROFILE BUILD FAILEDArray()CODE: 1    Resolving The Problem This problem is occurring because the... Read More

Problem Description When upgrading Nagios XI using the web interface the upgrade progress may stall with the message "Upgrade in progress". Sometimes you will need to clear this message manually due to unforeseen circumstances, this KB article... Read More

Problem Description You do not know the password for the nagiosadmin account and need to reset it.   Resetting The Password Open an SSH or direct console session to your Nagios XI host and execute the following command: /usr/local/nagiosxi/scripts... Read More

Problem Description You can access the Nagios XI interface, but can't seem to access the Core Configuration Manager.   Resolving The Problem Access the Admin >Reset Security Credentials page and reset the subsystem credentials. Run the... Read More

Overview Running out of HDD space on the Nagios XI server could create a large number of problems - disrupted monitoring, data loss, database corruption, inability to log in the web interface, tons of notifications, etc. If you receive warning or... Read More

Problem Description When looking at the location that the scheduled backups are stored in, there are no new xxxxxxx.tar.gz files being created in this location. Additionally,  in the /store/backups/nagiosxi/ location there are lots of folders that... Read More

Overview This KB article explains how to change the log level for Nagios XI Scheduled Backups. As of Nagios XI 5.4.4 you can define different levels of verbosity recorded in the scheduled backup log file.   Define Log Level The file /usr/local... Read More

Problem Description When you attempt to scheduled downtime for a host or service the downtime never appears despite being informed it was successfully added. In addition to this when you navigate to Home > Incident Management > Scheduled... Read More

Problem Description This KB article helps fix scheduled reports that are not running, you are not receiving the email that should be sent out.   Troubleshooting The first step is to check the contents of the apache crontab file with the following... Read More

Overview This KB article provides solutions to issues that can arise when uploading SNMP MIB files.     Permissions Some problems are caused by incorrect permissions on the SNMP MIB files. If you receive one of these errors: failed to convert to... Read More

Problem Description When starting or restarting the snmptt service you see output that looks like the following: Starting snmptt: add_mibdir: strings scanned in from /usr/share/snmp/mibs/.index are too large. count = 49 Cannot find module (SNMPv2-TC... Read More

Problem Description When upgrading Nagios XI above version 5.6.5, BPI checks which were dependent on hostgroups or servicegroups would change from their usual status to "Unknown BPI Group Index"..   Resolution The fix for this issue involves editing... Read More

Problem Description After upgrading to 2009R1.2C, some users started getting an error about SourceGuardian.   Resolving The Problem Add this line to your /etc/php.ini file: extension=ixed.5.1.lin   Once you make that change, restart Apache:... Read More

Problem Description This KB article explains how to resolve an error similar to the following that appears in the Nagios XI GUI: SQL Error [nagiosxi] : ERROR: syntax error at or near "localhost"LINE 1: ...ios XI','nagiosadmin',4,'... Read More

Problem Description In the Nagios XI interface, the Status Information shown for a service stops at 256 characters (anything after is cut off). When you look at the service in Nagios Core you can see the entire Status Information.   Explanation In... Read More

Overview This KB article is about the MySQL / MariaDB database and adjusting the STRICT_TRANS_TABLES setting. As of [MySQL 5.7.5] and [MariaDB 10.2.4] the STRICT_TRANS_TABLES mode is enabled by default. When this is enabled it causes database... Read More

Overview This KB article explains how to troubleshoot problems with reports taking a long time to run on your Nagios XI server.     Check Log Files When you are experiencing issues with reports the first step is to analyze the log files for the... Read More

Problem Description In Nagios XI when trying to delete or deactivate a host through the Core Configuration Manager, you may get the following error (or one similar to it) in a red box near the top of your screen:     Resolving The Problem In order... Read More

Problem Description This KB article shows you how to resolve issues with two factor authentication and not being able to login when it is enabled.     Confirm Correct Email Address Two factor authentication sends an email to the address associated... Read More

Problem Description When upgrading Nagios XI, the upgrade may fail with the error: The following error message is produced: root.crontab.orig: cannot overwrite existing file   This problem generally occurs when there are leftover files from... Read More

Problem Description After uploading a plugin (check_apc_pdu_load.sh for example), the following error is produced: The following error message is produced: -bash: ./check_apc_pdu_load.sh: /bin/bash^M: bad interpreter: No such file or directory This... Read More

Problem Description When you try to apply configuration, you see an error, similar to this one: Warning: Duplicate definition found for contact 'xi_default_contact'(config file '/usr/local/nagios/etc/contacts.cfg', starting on... Read More

Problem Description After running the Windows Server wizard you notice that the Windows memory usage checks have values that do not match up with the physical memory in the server.   Explanation The checks created by the wizard use the check_nt... Read More

Problem Description When a query is submitted with a correct set of credentials, but a user does not have access to the WMI class, absolutely NO output is returned by wmic.   Explanation When a Windows user is added to a group, that user is given an... Read More

Overview This KB article provides contains troubleshooting steps for Windows Management Instrumentation (WMI) problems.   Permission Denied You might experience this error message even though the plugin tests are successful in a terminal session:... Read More

Problem Description In Nagios you experience the following symptoms: Missing hosts or services or status data Takes a very long time to restart the Nagios process Unusually high CPU load A flood of messages in the /var/log/messages related to ndo2db... Read More

Overview Nagios Remote Plugin Executor (NRPE) is an agent used by Nagios XI for communicating with remote hosts. Remote hosts are operating systems like Linux and Windows.   This KB article explains: How Nagios XI sends requests to the NRPE Agent... Read More

The Problem The new openssl package on the latest versions of Centos / RHEL/ Ubuntu / Debian cause compatibility issues that cause the check_nrpe plugin to fail when checking Windows Hosts running NSClient++. Error Displayed CHECK_NRPE: (ssl_err != 5... Read More

Problem Description The Nagios application is not displaying the correct information. This commonly occurs after applying an update to the Nagios program.   Explanation Your web browsers cache has not been refreshed with the latest code since the... Read More

Overview This KB article explains how you can enable debug logging with the PHPMailer to troubleshoot SMTP mail sending problems. The PHPMailer is used in Nagios Fusion and Nagios XI for sending emails using SMTP. If your system is configured for... Read More

Slack Notifications Stopped Working If Slack integration with Nagios XI stopped working for you with an error similar to the one below: 500 Can't connect to iaitdepartment.slack.com:443 (SSL connect attempt failed with unknown errorerror... Read More

Issue: The SSL certificate won't validate properly because the certificate didn't include any subject alternative names. Adding SAN (Subject Alternative Name” into “Additional Attributes” field on a Microsoft Certificate Authority... Read More

Problem Description There are PHP notices and deprecated messages filling up the /var/log/httpd/ssl_error_log file. Resolving The Problem This problem can be eliminated by updating the php.ini file. The advisory messages do not indicate a fatal error... Read More

Issue: You had your NDO3 downgraded to NDO2DB in previous versions of Nagios XI 5.7.x and now want to upgrade to the latest version of NDO3 to take advantage of the performance improvements. Solution: Execute the following commands on your server:... Read More

Issue: If your VMWare checks experience timeouts or are unusually slow, you may be running out of available entropy (available random numbers) on the XI server. These random numbers are necessary for the VMWare Perl SDK to function properly/quickly.... Read More

Problem Description In rare circumstances you may come across the following error in your web browser when accessing one of the Nagios products: Content Encoding ErrorThe page you are trying to view cannot be shown because it uses an invalid or... Read More

Problem: In Nagios XI versions 5.4.0 and 5.4.1 there was a bug in the included Nagios Core version which caused a segmentation fault (crash) in some systems.   Resolution: First and foremost, please take an XI backup (and a VM snapshot if possible)... Read More