apport installed and running, otherwise the core won't be dumped. To make the description complete: 1. Add
CoreDumpDirectory /tmp/apachedumps/ to apache2.conf. 2. Create the directory and
sudo chown www-data /tmp/apachedumps it. 3.
sudo apt-get install apport and edit
/etc/default/apport to start apport automatically. 4. Add the line `www-data - ...