For those googlin': ( in my case -- Ubuntu 16.04 and 18.04 and a custom app ) /var/crash was still empty, so a quick way to handle core creation ( provided that you are e.g. using a relevant ulimit builtin setting ) was
sudo sysctl -w kernel.core_pattern=core.%u.%p.%t # to enable core generation
and
systemctl restart apport # to restore default apport settings
# which, by the way, were "|/usr/share/apport/apport %p %s %c %d %P" (wit
