Never, last election there online voter registration system crashed. This was after they guaranteed it, saying multiple failsafes were implemented, there would be no way for it to fail. Come election day 90% of the devices crashed. This was only to see if you are at the right voting station. I remember our station switched over to paper and I still believe it was one of the reasons the last election had the lowest amount of people voting, apart from also the disenfranchised voters.
Voting online will be a cluster fuck, not to mention how will you ensure it is safe and basically impossible to manipulate. Tom Scott had a great video about it, but even if such a system is implemented, going to be impossible to implement.
Even a dual system with paper and electronic copies caused issues with bush vs algore