Hi @drwpcom. I have not seen it mentioned as a suggestion in this or any other threads discussing the INTENT_MISMATCH error but for us, the problem was a conflict between Woocommerce settings and the plugin’s settings in combination with some incomplete conditional logic in the front-end javascript.
On our site, we have all “Account Creation” options disabled in WooCommerce/Settings/Accounts_&_Privacy so essentially all checkouts are guest checkouts.
However, we also had the “Allow customers to securely save their payment details” option turned on in WooCommerce/Settings/Payments/Square.
One might assume that the Square plugin checks that account creation is possible before displaying the Save to Account option or before attempting to store payment info, but it doesn’t.
The result is that the “Securely Save to Account” checkbox was visible to customers at checkout and inevitably some customers chose to Save. When the plugin attempts to save but can’t because there’s no account to save it to, it throws the INTENT_MISMATCH error.
It’s been a few days now since we turned off the “Securely Save” option and so far all orders have processed normally. This may not be the source of the problem for everyone but it may help some.
