Just sent Woocommerce a Ticket because after the recent update it messed up my ability to finalise orders at the Page where you put in contact details and shipping details.
I got this reply back,
I checked your site, and I see that when the checkout form is submitted, the site is returning HTTP error 500 as seen below:
We’re not able to replicate this on our test sites running the latest version of WooCommerce with the default Storefront Theme theme though.
I suspect your theme is causing a conflict here. I recommend running a conflict test to find the conflicting theme.