Update to version 2.5.0

Updates from Checkmk must always be performed from the last patch release of the source version to the last patch release of the target version. An update from 2.4.0p1 to 2.5.0-2026.03.27 therefore follows this path:

2.4.0p1   2.4.0p24   2.5.0-2026.03.27

Major versions cannot be skipped. If you want to update from 2.3.0 to 2.5.0, first perform an Update to version 2.4.0.

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As with any update to production software, you should check that your backups are up to date before performing the update of Checkmk.

Does this affect you? Yes.

What will you need to do? If you create your backups automatically via Setup > Maintenance > Backups, check there that your backups are up to date and that the most recent backup jobs have completed without errors.

For more information, see the articles on Backups and on Backing up and restoring sites.

Checkmk 2.5.0 requires slightly higher system resources than 2.4.0. It is therefore advisable to find out before updating which free capacity the servers used for Checkmk still have.

Does this affect you? Yes, but the extent to which you are affected depends heavily on how you use Checkmk.

What will you need to do? Make sure that there is sufficient free capacity available. For information on the expected changes in the use of hardware resources, refer to the following table:

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In Checkmk version 2.5.0, some outdated distributions are no longer supported.

Does this affect you? This will affect you if any of the following Linux distributions — still supported in 2.4.0 — is installed on your Checkmk server:

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Checkmk 2.5.0 uses new JavaScript features that are not available in older browsers. Which browsers are supported in which versions can be found in the System requirements.

Does this affect you? You will usually have automatic updates to the latest browser version enabled on desktop systems.

What will you need to do? Check the browser version you are using and install a more recent browser if necessary. If you are using single board computers, smart TVs or digital signage solutions to display dashboards and you have no control over the system browser, test that any required dashboards are displayed correctly before updating. If necessary, contact the hardware manufacturer for updates.

Up to Checkmk 2.2.0, every automation user could be logged in with a username and password passed via GET parameters. This option has been reduced as of Checkmk 2.3.0 and has been removed in version 2.5.0 (Werk #16223 and #17345).

Does this affect you? This change also primarily affects users who display dashboards using single board computers, smart TVs or digital signage solutions without a connected keyboard.

What will you need to do? Read the article on dashboards to learn how to enable sharing of individual dashboards in Checkmk starting with version 2.5.0.

Checkmk 2.5.0 updates Python to 3.13.9. This update affects modules installed to a Checkmk site. In many cases, post-installed modules are incompatible with Python 3.13.9. In the worst case, obsolete modules overwrite the functionality of the modules supplied by Checkmk.

Does this affect you? This will apply to you if Python modules have been installed later in your site. This may be the case, for example, if you have explicitly installed Python modules for special agents or agent-based check plug-ins that you have written yourself or obtained from the Exchange.

To find out if Python modules have been installed in your site, look for the dist-info and egg-info directories:

If the search result is not an empty list, you will need to take action.

Local files allow you to customize and extend the functionality provided by Checkmk. These files are located in the local part of the site directory structure, i.e. in ~/local and can be located in extension packages or simply 'lying around'. Local files can cause problems during an update if they no longer match the new Checkmk version.

Does this affect you? Since it is not possible for Checkmk to fully ensure the compatibility of local adaptations during an update, you should check your Checkmk site before an update to see whether local files are used, which ones they are and how they are organized.

First, use mkp list to search for extension packages (MKPs) present in the site.

Also use mkp find to get an overview of unpackaged local files in your Checkmk site.

If the output for one or both of these commands is not empty, you will need to take action.

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Does this affect you? The topic of APIs affects you if you have extended the check plug-ins delivered with Checkmk with your own, self-written plug-ins and/or if you use plug-ins from other sources.

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Deprecated endpoints or parameters of the Checkmk REST API are marked in the API documentation with the icon.

Does this affect you? This may affect you if you use the Checkmk REST API in your own scripts, for example.

What will you need to do? Open the REST API documentation with Help > Developer Resources > REST API documentation. Search for Deprecated in the browser on the page, check whether you are using deprecated elements in your scripts and replace them before updating. In the REST API documentation, you will usually find instructions on how to replace the functions that no longer exist in the new version.

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As in every Checkmk version, there are also changes to the software in the current 2.5.0 version which may have repercussions on your Checkmk installation. In Checkmk these changes are organized and documented in what we refer to as our Werks. A so-called incompatible change requires that you make manual modifications in order to allow existing functions to continue to run as usual and/or to be able to use new functions.

Does this affect you? In general, there will be incompatible changes that will also affect your Checkmk installation, it is however impossible to make a general statement. In this article we have collected those issues that apply to all or most Checkmk installations. In any case there may be additional changes that are relevant to you, for example in checks that you use in your installation.

What will you need to do? Following every update — including patch versions — Checkmk will show you the number and content of incompatible changes and ask you to check and take note of them. Before performing the update is the right time to check for any changes from version 2.4.0 that may have an impact on the update.

Starting with Checkmk 2.3.0, such Werks are no longer carried over, because by default only the Werks from the target version are displayed in Checkmk (Werk #15292). However, since Checkmk 2.5.0, all unconfirmed, incompatible Werks from the source version are copied during the update, so that information about these Werks is not lost during the update (Werk #15365).

It is also a good idea to get an overview of the incompatible changes in version 2.5.0 before the update: Open the list of Werks on the Checkmk website. In the description of a Werk, you will find information on what you may need to do to make the change compatible.

After you have carried out the update, the number and content of the incompatible changes will be displayed in the Checkmk interface and you will be asked to check and take note of them. Links help you to check so that you can find out with just a few clicks whether you are using an affected component. If it is certain that a Werk has no impact or you have made the required changes, confirm the Werk with Acknowledge.

In this section we describe the best practices that we follow even when updating large Checkmk environments. These are certainly not mandatory in every environment, but they can make the process of updating easier for you.

There are two different procedures for performing an update of all sites included in a distributed monitoring:

In particular, if you want to update while the system is running, you should read the notes in the general article on Updates and Upgrades.

Nothing fundamental has changed with the actual update of the software in Checkmk 2.5.0, i.e. you install the new version, perform the update of the Checkmk site, rectify any possible conflicts and check and confirm the incompatible changes.

Perform the update procedure as described in the article on Updates and Upgrades.

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We will present these changes in this User Guide’s articles — and in the Beginner’s Guide you will find a detailed introduction, including the most important elements of the user interface.

As with every major version, Checkmk 2.5.0 introduces a whole new set of check plug-ins. If you do not use the 'discovery check', i.e. the automatic update of the service configuration via the periodic service discovery, you will have to search for services on quite a number of hosts.

If your hosts are organized accordingly (e.g. in folders), you can generally use the Bulk discovery function for this. This function can be found under Setup > Hosts > Hosts and then in the Hosts > Run bulk service discovery menu.

In some cases, check plug-ins had to be moved out, or check plug-ins had to switch to new APIs.

Does this affect you? The risk of being affected is present if you monitor hardware with very long lifecycle, especially with special agents.

What will you need to do? If services disappear after the update, search the Werks for the manufacturer of the monitored products. In most cases, you will have to switch to new APIs or, in rare cases, use packages from the Exchange to monitor a specific hardware or software component.

Does this affect you? This will only apply to you if you have explicitly installed Python modules for special agents or agent-based check plug-ins that you have written yourself or obtained from the Exchange and have removed these in the course of preparing for the update.

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Since 2.3.0 Checkmk already contains a new active check for HTTP connections and certificates. The Check HTTP web service can be found under Setup > Services > HTTP, TCP, Email, …​ in the Networking box. The new check is significantly better performing, more robust and easier to configure than the previous Check HTTP service. In addition, it is now possible to monitor several things at once with a single rule, for example HTTP response code, response time and certificate validity.

In Checkmk 2.4.0 some rarely-used options within the old check have been added to the new check to make migration easier. Furthermore, we provide a migration script that maps existing calls and resulting services 1:1. With Checkmk 2.5.0, you can no longer configure new rules for the old check. It will be completely removed later.

Once the migration has been completed, you can achieve significant performance benefits by merging multiple rules, allowing a single execution of the check to produce multiple outputs, thus reducing CPU overhead. In many cases you can also generate multiple services using a single rule in the new check.

General information on the new check can be found in the two Werks #15514 and #15515. Werk #17725 describes the migration script. A detailed blog article explains the details of the possibilities, limitations and best practices for preparing and following up the migration.

If you come across applications in which the new check cannot replace the old one, you can display the command line used in the same way as in the procedure described here. You will then have the option of calling the old check, or a system-wide installed check_http via Setup > Other services > Integrate Nagios plugins.

The term management board stands for separate plug-in cards or extended BIOS functionality (Baseboard Management Controller/BMC, Management Engine/ME, Lights Out Management/LOM) for monitoring and managing the hardware in addition to the installed operating system.

Up to Checkmk 2.4.0, management boards can be configured in two ways: As a host property or as a separate host. As the configurability as a host property is very limited, in the future this option will no longer be available.

Since Checkmk 2.4.0, Redfish monitoring is an integral part of the software (Werk #17404). We explain additional background information and possible alternatives in the Monitoring management boards blog article.