How do I figure out why my Overcloud stack deployment failed?

Issue

• Overcloud stack deployment failed

openstack overcloud deploy  --templates /home/stack/templates/my-overcloud -e /usr/share/openstack-tripleo-heat-templates/environments/network-isolation.yaml -e /home/stack/templates/network-environment.yaml --control-flavor control --compute-flavor compute --control-scale 1 --compute-scale 1  --block-storage-scale 0 --ceph-storage-scale 0 --swift-storage-scale 0 --ntp-server pool.ntp.org --neutron-network-type "vlan" --neutron-disable-tunneling --neutron-network-vlan-ranges datacentre:3:2021 --timeout 40 --debug --log-file /home/stack/deployOct6.log