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Werk #19203: Fix GUI errors caused by RRD filenames exceeding filesystem limits

Component The Checkmk Micro Core
Title Fix GUI errors caused by RRD filenames exceeding filesystem limits
Date May 11, 2026
Level Trivial Change
Class Bug Fix
Compatibility Compatible - no manual interaction needed
Checkmk versions & editions
2.6.0b1
Not yet released
Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.5.0p3
Not yet released
Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

After upgrading from the Community Edition to the Pro Edition and switching to the Checkmk Micro Core, services with very long names could cause errors visible in the GUI. The CMC uses the MULTIPLE (XML) RRD format, and those long service names produced RRD filenames that exceeded the filesystem's NAME_MAX limit. The RRD tool then failed to process the generated XML file.

Starting with this release, the CMC validates every metric's RRD filename length against the filesystem limit before writing the XML file. Metrics whose filenames would be too long are skipped, and the corresponding XML file is not created if any metric fails the check. This prevents the RRD tool errors and the associated GUI problems.

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