How to fix WC-API and the PayPal Instant Payment Notification Error

This week I spent a couple of hours figuring out why I was receiving the following notifcation from PayPal via e-mail:

The solution was quite simple

Apparently, WooCommerce has a bug that allows you to set permalinks for products to: “/%product_cat%”. Basically, this breaks the WooCommerce API page in which it receives notifications from PayPal. It basically creates a 404 error, page not found. To fix it, is easy. Just include a bit of text before this tag: “products/%product_cat%”. Then the page will work again. You can also write some custom code to redirect WP to your product pages properly using the Rewrite API/add rewrite rule.

I did come across another suggestion.

You can check the Language Encoding for PayPal buttons (Profile and Settings > Selling Tools > PayPal button language encoding > More Options.

You then need to check the characters being sent to PayPal with yours and if it matches it should work.

Neither of these solutions work?

Make sure your running SSL 🙂

Find the error log to check what is going on

If this is not the problem then you can check your error log to see what is being communicated with PayPal. Usually you can find the error log:

• in your server’s root folder, called error.log
• in public_html or similar folder, called error.log
• in var/logs or similar, called error.log
• additionally, if you have debugging enabled in WordPress and you have it saved to a file, it will be in the wp-content folder, and called debug.log
• If you are having trouble finding the file then insert the following code into your template somewhere: <?php phpinfo(); ?> and search the page for the error_log value.