Werk #18156: Prevent site Apache stopped with syntax error due to undefined symbol
| Component | Other components | ||||||
| Title | Prevent site Apache stopped with syntax error due to undefined symbol | ||||||
| Date | Sep 12, 2025 | ||||||
| Level | Prominent Change | ||||||
| Class | Bug Fix | ||||||
| Compatibility | Compatible - no manual interaction needed | ||||||
| Checkmk versions & editions |
|
In previous versions of Checkmk, an update of the packages apache2 or apache2-bin would cause the site Apache to crash on the next reload.
This crash commonly occured at midnight, when a site rotates the Apache logs.
In such an instance, omd status would show that the site is partially running.
Moreover, the following error could be found in /omd/sites/cmk/var/log/apache/error_log:
[mpm_prefork:notice] [pid 2364] AH00171: Graceful restart requested, doing restart apache2: Syntax error on line 126 of /omd/sites/cmk/etc/apache/apache.conf: Cannot load /omd/sites/cmk/lib/apache/modules/mod_headers.so into server: /omd/sites/cmk/lib/apache/modules/mod_headers.so: undefined symbol: ap_set_content_type_ex
With this change, all OMD sites will be restarted after an update of the apache2 or apache2-bin packages.
This prevents the crash.
Background
The active Apache process is not able to gracefully reload after the apache or apache2-bin packages have been updated.
For this reason, distributions include post update triggers, e.g., /var/lib/dpkg/info/apache2.postinst.
These ensure that the system Apache is restarted after the update.
Checkmk now also includes these triggers to restart the site Apache.