Launcher sends me back to launch screen with an error.

What I expected to happen was...: to play minecraft with friends.
Describe what you thought should happen here
I would sign in and play minecraft with friends, with no problems.
What actually happened was...: i received an error
Describe what happened here
I signed in fine, and clicked launch and it sent me back to the launch screen with an error.
Steps to Reproduce:
1. Start Minecraft
2. Sign in
3. Click Launch
4. Receive error