Werk #22760: Interface groups: no interfaces reported

Component	Checks & agents
Title	Interface groups: no interfaces reported
Date	Oct 16, 2026
Level	Trivial Change
Class	Bug Fix
Compatibility	Compatible - no manual interaction needed
Checkmk versions & editions	3.0.0b1 Not yet released Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT 2.5.0p17 Not yet released Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT 2.4.0p38 Not yet released Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

If an interface group was configured (for example for the Linux interfaces via the ruleset "Network interface and switch port discovery") and the agent then reported no interfaces at all, the interface group service crashed with IndexError: list index out of range.

The service now goes to UNKNOWN with Item not found in monitoring data, as an ungrouped interface service does in the same situation.

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