woo commerce paypal express gateway

I updated new woo commerce 3. and now my paypal express gateway is not checking out
When you get to “review order” then says fatal error 105. It was suggested that I update paypal plug in to 1.2.0. But I don’t have the paypal plug in on my list of word press plug ins. The “paypal express gateway” is under the woo commerce plug in and is open source. I don’t see how I can update it?