Endless loading/spinner on the checkout page

The ‘review order’ page loads the payment methods/totals via ajax – this display a loading spinner briefly. If there are problems, this section may fail to load or the spinner may remain.
First you should check WooCommerce > System Status for errors – often errors will be highlighted.
Still having problems? Common causes and resolutions are listed below.

AJAX error due to WordPress settings.

The URL’s in Settings > General need to match – this is because AJAX requests don’t work across different domains:

These URL's must match

Other JavaScript errors and conflicts

Themes and plugins can often cause problems (especially poorly coded ones!) with JavaScript. To check for errors use your browser’s error console.

Chrome shows errors on its console

You can also check for conflicts by turning off other plugins and switching to the default WordPress theme – this will often reveal the problem.