OCE Unexpected Platform Error

Played a few games today. Suddenly when I'm choosing my masteries in champion select I get a big saying "Unexpected Platform Error".

No masteries work. I cant create new masteries.

When I select a mastery, I get this popup. I click ok. My masteries are locked in. The game begins. It says I have no masteries set.

I am forced to play rank with no masteries.