Apache fails to start, Address already in use (but not really)

cforcode91
C Code Nov 08, 2017 Tutorial

I got this error on a fresh install when starting apache2 Ubuntu 12.10.

It's a bug in the apache2. It gets hung in the background. Here is my walkthrough to where the bugs might be in the software.

Here's the error I got:

el@titan:~$ sudo service apache2 start
 * Starting web server apache2               
(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs
Action 'start' failed.
The Apache error log may have more information.
                                                                         [fail]

Address already in Use? What could be using it? Check it out:

el@titan:~$ grep -ri listen /etc/apache2
/etc/apache2/apache2.conf:#   supposed to determine listening ports for incoming connections, and which
/etc/apache2/apache2.conf:# Include list of ports to listen on and which to use for name based vhosts
/etc/apache2/ports.conf:Listen 80
/etc/apache2/ports.conf:    Listen 443
/etc/apache2/ports.conf:    Listen 443

That means apache2 is preventing apache2 from starting. Bizarre. This will confirm:

el@titan:~$ ps -ef | grep apache2
root      1146   954  0 15:51 ?        00:00:00 /bin/sh /etc/rc2.d/S91apache2 start
root      1172  1146  0 15:51 ?        00:00:00 /bin/sh /usr/sbin/apache2ctl start
root      1181  1172  0 15:51 ?        00:00:00 /usr/sbin/apache2 -k start
root      1193  1181  0 15:51 ?        00:00:00 /bin/bash /usr/share/apache2/ask-for-passphrase 127.0.1.1:443 RSA
el        5439  5326  0 16:23 pts/2    00:00:00 grep --color=auto apache2

Yes, in this case apache2 is running, I was trying to start apache2 a second time on the same port.

What confuses me is that service reports that apache2 is NOT running:

el@titan:~$ sudo service apache2 status
Apache2 is NOT running.

And when you query apache2ctl for its status, it hangs.

root@titan:~# /usr/sbin/apache2ctl status
**hangs until Ctrl-C is pressed.

So Ubuntu seems to be having trouble managing apache2 on bootup. Time to stop apache2:

root@titan:~# /usr/sbin/apache2ctl stop
httpd (no pid file) not running

A big clue! You try to stop apache2 and it lost the process id! So Ubuntu can't stop apache2 because it doesn't know where it is!

You would think a reboot would fix it, but it doesn't because apache2 starts on boot and hangs. The normal boot process for apache2 is not working right.

So How to fix it?

I was able to fix this by analyzing the ps command output. Notice that the ps command tells us that that process was started by "/etc/rc2.d/S91apache2 start".

That is the offending program that needs a swift kick.

/etc/rc2.d/S91apache2 is the symbolic link used to start apache2 for you when the computer starts. For some reason it seems to be starting apache2 and then hangs. So we'll have to tell it to not do that.

So go take a look at that /etc/rc2.d/S91apache2.

el@titan:/etc/rc2.d$ ls -l
lrwxrwxrwx   1 root root    17 Nov  7 21:45 S91apache2 -> ../init.d/apache2*

It's a symbolic link that we don't want it to be there. Do this to prevent apache2 from starting on boot:

root@titan:~# sudo update-rc.d -f apache2 remove
 Removing any system startup links for /etc/init.d/apache2 ...
   /etc/rc0.d/K09apache2
   /etc/rc1.d/K09apache2
   /etc/rc2.d/S91apache2
   /etc/rc3.d/S91apache2
   /etc/rc4.d/S91apache2
   /etc/rc5.d/S91apache2
   /etc/rc6.d/K09apache2

Reboot the computer to make sure apache2 doesn't start and hang. Ok good. Now you COULD put apache2 back the way it was, but that would make it fail again.

root@titan:~$ sudo update-rc.d apache2 defaults     //(don't do this)
 Adding system startup for /etc/init.d/apache2 ...
   /etc/rc0.d/K20apache2 -> ../init.d/apache2
   /etc/rc1.d/K20apache2 -> ../init.d/apache2
   /etc/rc6.d/K20apache2 -> ../init.d/apache2
   /etc/rc2.d/S20apache2 -> ../init.d/apache2
   /etc/rc3.d/S20apache2 -> ../init.d/apache2
   /etc/rc4.d/S20apache2 -> ../init.d/apache2
   /etc/rc5.d/S20apache2 -> ../init.d/apache2

Instead, start the apache2 like this:

sudo service apache2 start

And the apache2 is back up and serving pages again. There seems to be some serious bugs with apache2/Ubuntu 12.10 that causes apache2 to start and hang. This is a workaround, I suppose the fix is to get newer versions of apache2 and Ubuntu and hope for the best.

 

Source: https://askubuntu.com/a/377713