Hey Joj,
I found my problem in out of date woocommerce php files. Check your woocommerce system status and look for out of date template files. That may be your problem.
I had to add the updated WooCommerce folder to my theme folder on my desktop. I then re-uploaded my theme zip folder with the help of “Easy Theme and Plugin Upgrades.” Once I updated all my files, my users could login/register.
Is this helpful?