Same here. Played it last night, came home from work today, and got the error message everyone else is getting, "Could not find or load main class net.minecraft.client.main.Main"
Antergos Linux release 17.7 ARCH Linux 4.13.8-1 Minecraft Launcher 1.6.82-j OpenJDK 8
Dirk
Working for me again on KDE Arch linux using Minecraft Launcher 1.6.84-j. Woohoo! Thanks!!