WooCommerce PayPal Express Checkout Gateway causing “Internal Server Error”

Hi.

I am using WooCommerce PayPal Express Checkout Gateway v1.1.2 for an online store.

The process is that the person goes to the basket, then clicks on “check out with PayPal”, they then log in to their PayPal account and click “continue”, which takes them back to my website to the “confirm your PayPal order” page where they then click “Place Order”, then the page automatically scrolls back to the top where there is now an “Internal Server Error” message.

I repeatedly try doing the same transaction over and over again and the error occurs about 50% of the time. The correct payments & notifications occur regardless of whether an “Internal Server Error” occurs or not. I can’t understand why the error is happening, and also why it should not occur all the time given that I am making exactly the same purchase each time.

I added:
define( ‘WP_DEBUG’, true );
define( ‘WP_DEBUG_LOG’, true );
to my wp-config.php file in the correct section but it does not generate any debug log file.

I can’t launch my online store with this error occurring so often. Can someone please help me.

Thanks.