Kierkegaard wrote a book entitled "The Sickness Unto Death (1849)." It was meant to be instruction for people to learn to overcome despair by being willing to be themselves, however, I took it as a kind of epitaph for humanity. Kierkegaard, of course, was a Christian philosopher, while I am an atheist.
By existential void, I mean the idea of nothingness in the face of humanity's persistence in collective illusions that protect them from the nothingness following death. In a similar vein, Sartre wrote that humanity was a useless passion. Pascal proposed that humans accept the wager that in the end belief, faith, will prove correct rather than unbelief. The latter, I think, he assumed would be unbearable.
For me, unbelief is preferable because it can cast a human back away from belief systems that prevent people from focusing on non-supernatural, non-illusory natural cause and effect relations. Looking to material cause and effect relations rather than to some one of the thousands of fabricated gods and superstitions can result in humans discerning how our common existence can be made more endurable during our brief life spans on earth and more viable for all of nature as well.
For me, the remedy for "sickness unto death", or the underlying existential despair common to all humans with awareness of existence, is to accept the finality and frailty of our earth-bound lives and to resolve to work together with compassion for our own and for the common existence of all nature.
A profound acceptance of the existential void is the only viable path toward preventing our own and nature's eventual extinction.