" Mainclass net.minecraft.client.main.Main" Could not be found, Exit code 1

I tried to start Minecraft (Java) some days ago, but i have since got the same error everytime.

I have not started the program for a couple months, so it could be because of an update.

I have tried to reinstall Minecraft (including the launcher) and Java multiple times but nothing changed.

(When I reinstall the launcher and then click on play, the download bar starts already at 50% even though i deleted the .minecraft files in Roaming prior to reinstalling, i don't know if that has something to do with it)