LiteSpeed is a fast web server that can be used as drop in replacement for Apache on Cpanel servers.

If you are running LiteSpeed, make sure license key is active, if it ever get disabled/expired for whatever reason, LiteSpeed stop doing its job, making all web sites down.

To change license key on a LiteSpeed server, run

echo "YOUR-LICENSE-KEY" > /usr/local/lsws/conf/serial.no

Update license with

/usr/local/lsws/bin/lshttpd -r

Restart LiteSpeed with

/usr/local/lsws/bin/lswsctrl restart

Example

[root@server1 ~]# /usr/local/lsws/bin/lshttpd -r
2017-09-26 08:08:54.789 [NOTICE] Memory size is: 98824896KB.
2017-09-26 08:08:54.959 [NOTICE] [OK] Updated license key has been created at /usr/local/lsws/conf/license.key.
[root@server1 ~]# /usr/local/lsws/bin/lswsctrl restart
[OK] Leased license key 1 will expire in 36 days!
[OK] litespeed: pid=10213.
[root@server1 ~]# 

See LiteSpeed