" Could not find or load main class " Bug

The newest launcher does not work for me. So I go to minecraft.net, and start-up minecraft via the old launcher. I have been doing that for the past 3-4 months. Now all the sudden it does not work. If it is not a mojang bug, please share any - all knowledge about how to fix this issue with me. Here is a picture of what it says in the launcher.

Pictures:

https://gyazo.com/293cc45d49966db671f980ccce21a88a