(98)Address already in use: make_sock: could not bind to address 0.0.0.0:443

When starting the httpd service, the following error message appears and the service failed to start.

# service httpd start
Starting httpd: (98)Address already in use: make_sock: could not bind to address 0.0.0.0:443
no listening sockets available, shutting down
Unable to open logs

The error message means that when the httpd tried to start, some other process was already listening on 443. To see what other processes are using port 443, the following two commands may be used:

# netstat -A inet -lnp
# lsof -i tcp:443