Checkout infinite loader problem

Hello sir, There are two problem at checkout page im struggle with, one of them is infinete loader problem, when i click to pay button the loader came up and keep going forever nothing will happen. When I reload the page, and click the pay button again then it works. I cant figure out why this happen.

And other problem is in different website when i click to pay button the button does not respons nothing happen in the page but i see the order in order history

Im waiting for your answers ,Thank a lot have a nice day.