源自：https://access.redhat.com/solutions/2710411

故障描述：

-- Unit httpd.service has begun starting up.
Apr 19 22:57:30 centreon-upgrade-test httpd[8346]: AH00534: httpd: Configuration error: No MPM loaded.
Apr 19 22:57:30 centreon-upgrade-test systemd[1]: httpd.service: Main process exited, code=exited, status=1/FAILURE
Apr 19 22:57:30 centreon-upgrade-test systemd[1]: httpd.service: Failed with result 'exit-code'.
-- Subject: Unit failed
-- Defined-By: systemd
-- Support: https://access.redhat.com/support

解决方案：

对于httpd 2.4, mpm通常默认加载在conf.modules.d/00-mpm.conf中。它应该包含在httpd.conf中，如下所示:

Include conf.modules.d/*.conf 

如果该文件被删除或不包含，那么您仍然需要加载您选择的mpm, prefork, worker或事件，如下所示:

# Select the MPM module which should be used by uncommenting exactly
# one of the following LoadModule lines:

# prefork MPM: Implements a non-threaded, pre-forking web server
# See: http://httpd.apache.org/docs/2.4/mod/prefork.html
#LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

# worker MPM: Multi-Processing Module implementing a hybrid
# multi-threaded multi-process web server
# See: http://httpd.apache.org/docs/2.4/mod/worker.html
#
LoadModule mpm_worker_module modules/mod_mpm_worker.so

# event MPM: A variant of the worker MPM with the goal of consuming
# threads only for connections with active processing
# See: http://httpd.apache.org/docs/2.4/mod/event.html
#
#LoadModule mpm_event_module modules/mod_mpm_event.so