28.8 Troubleshooting
If Apache does not start, the Web page is not accessible, or users cannot
connect to the Web server, it is important to find the cause of the
problem. Here are some typical places to look for error explanations and
important things to check.
First, rcapache2 (described in
Section 28.3, Starting and Stopping Apache) is verbose about errors, so can
be quite helpful if it is actually used for operating Apache. Sometimes
it is tempting to use the binary /usr/sbin/httpd2
for starting or stopping the Web server. Avoid doing this and use the
rcapache2 script instead. rcapache2
even provides tips and hints for solving configuration errors.
Second, the importance of log files cannot be overemphasized. In case of
both fatal and nonfatal errors, the Apache log files, mainly the error
log file, are the places to look for causes. Additionally, you can
control the verbosity of the logged messages with the
LogLevel directive if more detail is needed in
the log files. By default, the error log file is located at
/var/log/apache2/error_log.
HINT: A Simple Test
Watch the Apache log messages with the command tail -F
/var/log/apache2/my_error_log. Then
run rcapache2 restart. Now, try to connect with a
browser and check the output.
A common mistake is not to open the ports for Apache in the firewall
configuration of the server. If you configure Apache with YaST, there
is a separate option available to take care of this specific issue (see
Section 28.2.2, Configuring Apache with YaST). If you are configuring
Apache manually, open firewall ports for HTTP and HTTPS via YaST's
firewall module.
If the error cannot be tracked down with the help of any these, check the
online Apache bug database at
https://httpd.apache.org/bug_report.html. Additionally, the
Apache user community can be reached via a mailing list available at
https://httpd.apache.org/userslist.html. A recommended
newsgroup is comp.infosystems.www.servers.unix.
