How do I fix a broken PayPal button that freezes on the loading spinner?

A PayPal button freezes when the secure checkout token handshake fails, when browser cookies block the third-party login popup, or when outdated theme scripts interrupt PayPal’s Javascript SDK on your product page.

“More often than not, it’s a token handshake silently failing, or an old script fighting with PayPal’s SDK. I’ll pin down which one’s happening on your site and have the button working again within 24 hours for $99.”
— Jeff Bollettino, Managing Director, Ignite Conversions