I am on a Mac and use the jar launcher. But when I download any mod-pack for example I'll use all the mods 4. The jar launcher appears and then i press play but then the game immediately crashes. And it also crashes when i choose to make my own 1.14.4 modpack.
Here is the log from trying to play ATM4
Here is the log from trying a no mods modded 1.14.4