Werk #18763: ups_in_voltage, ups_out_voltage: Fix crash when UPS reports a non-numeric voltage

Component	Checks & agents
Title	ups_in_voltage, ups_out_voltage: Fix crash when UPS reports a non-numeric voltage
Date	Aug 19, 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 2.5.0p13 Not yet released Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT 2.4.0p36 Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

Some UPS devices report an empty value, or the literal NULL, for the input or output voltage of a phase. This made the service discovery of the affected host fail completely with

ValueError: invalid literal for int() with base 10: ''
ValueError: invalid literal for int() with base 10: 'NULL'

so no service was discovered on that host at all, not just the IN voltage phase ... and OUT voltage phase ... services.

Phases without a numeric voltage are now ignored instead of crashing. All phases that do report a voltage are discovered and monitored as before. A phase that stops reporting a voltage after it has been discovered goes UNKNOWN with "Item not found in monitoring data" until the host is re-discovered.

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