I occasionally buy stuff off Rakuten. It’s mostly just herbs, but gradually points do build up. I also have a Kobo Libra reader. Kobo is a subsidiary of Rakuten, so you can log in with a Rakuten account and all that “integration.”

The other day I noticed that finally the newest volume of No Game No Life came out, so I went to get it. That took unexpected effort. The payment process just kept failing with an extremely unhelpful “we can’t complete this transaction” error. Naturally it wouldn’t say what was wrong, even though as it turns out it was their system’s brainfart.

The reason was that I dared to try using Rakuten points as part of the payment. Not the whole (I only have a few hundred points, so I couldn’t even if I wanted to), just so the credit card payment would be “round.” Turns out their system can’t handle such a complicated errand despite offering it in the UI.

As a good debugger I started with re-login, then disabling my uBlock Origin and Firefox Advanced Protection, but none of that helped (in exchange I noticed that they have “social” links on their checkout page, sending requests to fucking Pinterest). But as soon as I removed the point usage (with the “Clear” button) the checkout succeeded in half a second.