The path to the log file for error messages. Usually, it is
logs/error_log, which is relative to the ServerRoot. Often the
directory logs in ServerRoot is a symbolic link to
/var/log/httpd. Then the log path above would result in error
messages being logged to /var/log/httpd/error_log.
You should monitor this log after reconfiguring, since most configuration errors are logged here (Linuxconf, sadly, catches only a few of them.) Additionally, any failed accesses by clients (non-existent pages, failed authorization and so on) are also logged here.