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Werk #18998: Fix time zone handling for autodiscovery excluded time windows

Component Setup
Title Fix time zone handling for autodiscovery excluded time windows
Date Apr 16, 2026
Level Trivial Change
Class Bug Fix
Compatibility Incompatible - Manual interaction might be required
Checkmk versions & editions
2.6.0b1
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.5.0b5
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.4.0p27
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.3.0p47
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Ultimate MT

Checkmk allows configuring time windows during which automatic host discovery should not run. Due to a bug, the Checkmk server's local time zone was not taken into account when evaluating these windows: the comparison was done against UTC rather than local time. On servers not running in UTC, this caused the exclusion windows to be applied at the wrong hours.

This has been fixed by using local time for the comparison.

If your Checkmk server is not running in UTC and you have configured excluded time windows for automatic discovery, you should review those windows to ensure they reflect the intended local times.

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