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Werk #19753: Fix matching of notifications in rule-based notification processing

Component Notifications
Title Fix matching of notifications in rule-based notification processing
Date Apr 15, 2026
Level Prominent 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

Previously, rule-based notifications had two related issues:

If a contact was a member of multiple contact groups and separate notification rules targeted these groups with the same plugin and parameters, the contact could receive duplicate notifications. This also affected bulk notifications.

Additionally, if two rules matched the same set of contacts for the same plugin but with different parameters, the second rule silently overwrote the first one's settings instead of creating a separate notification. This meant notifications configured by earlier rules could get lost.

Both issues have been fixed. Contacts from different rules with identical notification settings are now properly merged, and rules with different parameters create separate notifications as intended.

Action required

If your setup relied on later rules overriding earlier ones for the same contacts and plugin, you may now see additional notifications since both rule configurations will be delivered. Review your notification rules and remove any that were previously overridden. If you had workarounds in place to deal with duplicate notifications (e.g. cancel rules), those may no longer be needed.

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