It's not letting me on 1.8 or above

Put the summary of the bug you're having here
It's not letting me on 1.8 or above it says Expected BEGIN_ARRAY but was STRING at line 1 column 1
What I expected to happen was...:
Describe what you thought should happen here
to get on minecraft 1.8.3
What actually happened was...:
Describe what happened here
It went back to launcher and is not getting on
Steps to Reproduce:
1. try to access 1.8 or above
2. ...
3. ...