I followed instructions from Turbo, but I'm loosing all my config and existing worlds doing this. When I try to copy it back from older `minecraft` folder, then it's broken again. I would need some instructions about files which need to be copied back after this operation. But now I cannot play MineCraft at all. I have this issue on both my iMac and MacBook. Where only one of them uses mods and shaders. Second one is used only to play with original settings. But both are affected.
I think that this issue has been fixed. I can play again.