Werk #20040: Fix removed services reappearing after a failed discovery rescan
| Component | Core & setup | ||||
| Title | Fix removed services reappearing after a failed discovery rescan | ||||
| Date | Jul 17, 2026 | ||||
| Level | Trivial Change | ||||
| Class | Bug Fix | ||||
| Compatibility | Compatible - no manual interaction needed | ||||
| Checkmk versions & editions |
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Previously, when data fetching for service discovery failed, removed services could come back: After a user triggered a rescan, saw all services listed as vanished, and removed them, the just-removed services reappeared as undecided ("new") services once the discovery page reloaded.
The cause was cache handling. Checkmk only cached the source data after a successful fetch. When a user's rescan failed (e.g. a host unreachable or down), the previous (still populated) cache remained on disk. The reloaded discovery page then read that stale cache and re-discovered exactly the services that were just removed.
Checkmk now discards the data source cache when a fetch fails. After a failed rescan the discovery page reports the data source problem No cached data available instead of resurrecting outdated data. Thus, removed services stay removed.