Syntax error on line 2 of /etc/apache2/conf.modules.d/280_mod_proxy.conf: Cannot load modules/mod_proxy.so into server:

Symptoms

Apache cannot start on its own. When you attempt to restart manually, it shows an error that indicates an issue with the mod_proxy module:

Jan 1 00:00:00 hostname restartsrv_httpd[3672908]: httpd: Syntax error on line 28 of /etc/apache2/conf/httpd.conf: Syntax error on line 2 of /etc/apache2/conf.modules.d/280_mod_proxy.conf: Cannot load modules/mod_proxy.so into server: /etc/apache2/modules/mod_proxy.so: : ap_get_pollfd_from_conn

Description 

In rare circumstances, the core modules installed with cPanel may have issues that prevent Apache from properly building a new configuration or restarting. Reinstalling Apache will reinstall all core modules and restore the server to a working state.

Workaround

1. Run the following command from the command line to reinstall the default Apache modules:
   

   AlmaLinux, RockyLinux, CloudLinux 8:

   dnf reinstall ea-apache24

   AlmaLinux, CentOS, CloudLinux 7:

   yum reinstall ea-apache24

2. Make sure the module is enabled in its configuration file:

   [root@aerver ~]# cat /etc/apache2/conf.modules.d/280_mod_proxy.conf
   # Enable mod_proxy
   LoadModule proxy_module modules/mod_proxy.so

3. If the LoadModule line has been commented out, remove it with a text editor and reload the Apache configuration:

   /scripts/rebuildhttpdconf