Apache2 vhost config not working (Debian 7)

Question

My Apache 2.4.9 vhost configuration is not working any more on Debian 7.

I didn't make any changes and it seems to have broken.

Going to my site shows the following in /var/log/apache2/error.log

AH00052: child pid 5457 exit signal Segmentation fault (11)

What is the best way to trace what is causing this?

Also within /etc/apache2/sites-enabled is the following:

lrwxrwxrwx 1 root root 38 Jul 22 00:51 serverkb.co.uk.conf -> ../sites-available/serverkb.co.uk.conf

This used to just work as serverkb.co.uk , and all my other sites are still working without .conf even though I am on Apache 2.4.9 . I have already edited /etc/apache2/apache2.conf to say:

IncludeOptional sites-enabled/

instead of

IncludeOptional sites-enabled/*

And this is already in place:

<Directory /home/vhosts>
#       AllowOverride All
        Require all granted
</Directory>

Also, apache2ctl -S returns the following (some cut off on purpose):

VirtualHost configuration:
*:80                   is a NameVirtualHost
     default server dldmz.eu (/etc/apache2/sites-enabled/000-default.conf:1)
     port 80 namevhost dldmz.eu (/etc/apache2/sites-enabled/000-default.conf:1)
     port 80 namevhost byrongalietta.co.uk (/etc/apache2/sites-enabled/byrongalietta.co.uk:1)
             alias www.byrongalietta.co.uk
     port 80 namevhost bywatercraft.co.uk (/etc/apache2/sites-enabled/bywatercraft.co.uk:1)
             alias www.bywatercraft.co.uk
     port 80 namevhost dldmz.eu (/etc/apache2/sites-enabled/dldmz.eu:1)
             alias www.dldmz.eu
     port 80 namevhost myvideostation.co.uk (/etc/apache2/sites-enabled/myvideostation.co.uk:1)
             alias www.myvideostation.co.uk
     port 80 namevhost serverknowledgebase.co.uk (/etc/apache2/sites-enabled/serverknowledgebase.co.uk:1)
             alias www.serverknowledgebase.co.uk
ServerRoot: "/etc/apache2"
Main DocumentRoot: "/var/www/html"

Firstly, it is showing the wrong DocumentRoot of /var/www/html , but this isn't what is loading for serverkb.co.uk as I tested using a test.txt + phpinfo.php page

Here is the 000-default as well as serverkb.co.uk sites-available config files:

cat /etc/apache2/sites-enabled/000-default.conf

<VirtualHost *:80>
        ServerAdmin remove@snotneeded.com

    DocumentRoot /home/vhosts
    <Directory />
            Options FollowSymLinks
            AllowOverride None
    </Directory>

    <Directory /home/vhosts>
            Options Indexes FollowSymLinks MultiViews
            AllowOverride All
            Order allow,deny
            allow from all
#               Require local
##              Require all granted
    </Directory>

    ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
    <Directory "/usr/lib/cgi-bin">
            AllowOverride None
            Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
            Order allow,deny
            Allow from all
    </Directory>

    ErrorLog ${APACHE_LOG_DIR}/error.log

    # Possible values include: debug, info, notice, warn, error, crit,
    # alert, emerg.
    LogLevel warn

    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

EDIT: Looks like my friend left the unstable distribution sid in sources.list so it upgraded Apache and PHP. Now disabled, downgraded Apache and PHP and my sites are working again as normal.