Werk #19063: Prevent invalid regex when combining expressions

Component

Checks & agents

Title

Prevent invalid regex when combining expressions

Date

Jan 13, 2026

Level

Trivial Change

Class

Bug Fix

Compatibility

Compatible - no manual interaction needed

Checkmk versions & editions

2.6.0b1 Not yet released	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)
2.5.0b1 Not yet released	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)
2.4.0p20	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)
2.3.0p43 Not yet released	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)

Werk 17075 introduced a fix that prevented expressions from becoming invalid during concatenation when they contained global flags.

However, this fix was not applied everywhere. The "Check_MK Discovery" was still affected and would show a UNKN state with this error message:

"Invalid regular expression '...': global flags not at the start of the expression at position 1"

Now, the fix from werk 17075 is also applied for periodic service discovery. No manual interaction is required to benefit from this fix.