Werk #19829: Fix GUI crash caused by custom sidebar elements from Checkmk
| Component | User interface | ||||||
| Title | Fix GUI crash caused by custom sidebar elements from Checkmk <= 2.0 | ||||||
| Date | Jul 20, 2026 | ||||||
| Level | Trivial Change | ||||||
| Class | Bug Fix | ||||||
| Compatibility | Compatible - no manual interaction needed | ||||||
| Checkmk versions & editions |
|
Updating a site to Checkmk 2.4 could crash the GUI for all users of the site as soon as a single user profile still contained a custom sidebar element that was created with Checkmk 2.0 or older. After logging in, users only saw an error like:
Internal error: 1 validation error for CustomSnapinsModel custom_snapin.1.rows
Field required [type=missing, input_value={'context': {...}}, input_type=dict]
In Checkmk 2.0 and older, more snap-in types could be used as a base for custom sidebar elements (for example the host matrix). Since version 2.1 such elements were silently ignored, so they could survive unnoticed in user profiles for years. Checkmk 2.4 started to validate all stored custom sidebar elements when rendering the sidebar, which made the whole GUI crash on these leftovers.
The GUI no longer crashes if it encounters an invalid stored custom sidebar
element (or any other invalid customized page). The stored configuration is
left untouched: the affected element is skipped and a warning naming the
affected user and element is written to var/log/web.log instead.
No manual action is needed.