I only changed the launcher and everything worked but it is no longer snowing. It is raining in the snow but it is no longer snowing. It was snowing at the beginning but not anymore.
I'm not playing on a server!
Try / toggledownfall in the snow biom
It does not work.
Why is the snow so important?
Create a new world but switch the settings to "Cheats on"
You can try to see if the snow is activated in the settings.
/ weather rain
Otherwise it should snow in mountains from about 90
This has to be global warming, let's see the effects: it even spills over from the real to the virtual world.