After the free WP-Stripe plugin stopped working mid-month, we switched to a paid solution (Stripe Checkout Pro) and came up with a different error. This time, the .js required by Stripe isn't loading. I've tried manually adding it to the theme to force it to load (added the script tags calling the checkout.stripe.js file in the header.php file) and no luck. Switching themes to the WP default 2015 theme does make the plugin work, so there is something in the theme that is not playing well with the plugin. Any ideas as to what it might be? The page on which the plugin is being called is at https://www.ottawalibrary.org/donate/. I can see the call for the javascript in the header for that page, but between the plugins creator and me, we can't figure out what is keeping it from working with this theme. Any help is appreciated! Thanks,

Without the plugin and it's instructions I'd be guessing

I can't help you with the theme issue, other than to say that I've got Stripe working on an Atahualpa site using Gravity Forms and their Stripe add-on.