I installed Apache2, MySQL, and phpMyAdmin. All was well until I installed Yast2-http-server. When I try to restart the apache2 service I get the following error:
apache2.service - The Apache Webserver
Loaded: loaded (/usr/lib/systemd/system/apache2.service; enabled)
Active: failed (Result: exit-code) since Mon 2014-03-17 22:40:26 PDT; 2min 25s ago
Process: 4002 ExecStop=/usr/sbin/start_apache2 -D SYSTEMD -DFOREGROUND -k graceful-stop (code=exited, status=1/FAILURE)
Process: 3984 ExecStart=/usr/sbin/start_apache2 -D SYSTEMD -DFOREGROUND -k start (code=exited, status=1/FAILURE)
Main PID: 3984 (code=exited, status=1/FAILURE)

Mar 17 22:40:26 linux-61hu start_apache2[3984]: AH00526: Syntax error on line 48 of /etc/apache2/ssl-global.conf:
Mar 17 22:40:26 linux-61hu start_apache2[3984]: SSLSessionCache: 'shmcb' session cache not supported (known names: ). Maybe you need to load the appropriate socache module (mod_socache_shmcb?).
Mar 17 22:40:26 linux-61hu systemd[1]: apache2.service: main process exited, code=exited, status=1/FAILURE
Mar 17 22:40:26 linux-61hu start_apache2[4002]: AH00526: Syntax error on line 48 of /etc/apache2/ssl-global.conf:
Mar 17 22:40:26 linux-61hu start_apache2[4002]: SSLSessionCache: 'shmcb' session cache not supported (known names: ). Maybe you need to load the appropriate socache module (mod_socache_shmcb?).
Mar 17 22:40:26 linux-61hu systemd[1]: apache2.service: control process exited, code=exited status=1
Mar 17 22:40:26 linux-61hu systemd[1]: Failed to start The Apache Webserver.
Mar 17 22:40:26 linux-61hu systemd[1]: Unit apache2.service entered failed state.

The error_log shows where the error is and what you have to do to rectify it. I.e you need to load the mod_socache_shmcb.so module.
Have a look here for more details.