Werk #18119: Fix tag drop-down with a single choice

Component

Setup

Title

Fix tag drop-down with a single choice

Date

Jun 4, 2025

Level

Trivial Change

Class

Bug Fix

Compatibility

Incompatible - Manual interaction might be required

Checkmk versions & editions

2.5.0b1 Not yet released	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)
2.4.0p5	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)
2.3.0p35	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)

After the changes made in Werk #17836, some additional legacy code needed to be removed to support tag options when there is only one choice available.

This may have created rules with the null value set, which is not supported anymore. Therefore, running cmk-update-config is needed to run post update. This will remove the null tag from existing rules.

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