Unable to rebuild httpd.conf: "Configuration error: No MPM loaded."

Symptoms

When attempting to rebuild the Apache httpd.conf file, you receive an error:

CONFIG_TEXT: The “/usr/sbin/httpd -DSSL -t -f /etc/apache2/conf/httpd.conf.work.a8f4b0eb.cfgcheck -C Include "/etc/apache2/conf.modules.d/*.conf"” command (process 27196) reported error number 1 when it ended.
AH00534: httpd_ls_bak: Configuration error: No MPM loaded.
Rebuilding configuration without any local modifications.

Cause

This is caused by a misconfiguration of the installed Multiprocessing Module (MPM) for Apache. If all MPM modules have their "LoadModule" directives commented out, the Apache server will fail to load the required components when starting.

Resolution

Verify that the "LoadModule" line of the currently installed MPM is active in the configuration file.

1. Access your server through SSH as the root user.

2. Search the MPM configuration files for the "LoadModule" entry:

   # grep -riH 'loadmodule' /etc/apache2/conf.modules.d/000_mod_mpm*
   /etc/apache2/conf.modules.d/000_mod_mpm_worker.conf.rpmsave:#LoadModule mpm_worker_module modules/mod_mpm_worker.so
   /etc/apache2/conf.modules.d/000_mod_mpm_prefork.conf:#LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

3. The server should only have a single MPM module installed and active. You can confirm which MPM is currently intended in WHM / Software / EasyApache4 / Apache MPM.

4. Using the MPM configuration file that matches the MPM selected in EasyApache4, open the file in a text editor, and remove the comment character '#' from the beginning of the line, for example:

   CONFIG_TEXT: # LoadModule mpm_prefork_module modules/mod_mpm_prefork.so

5. Save the file and rebuild the Apache configuration:

   # /scripts/rebuildhttpdconf

6. Restart the Apache server:

   # /scripts/restartsrv_httpd