Domains in text is fictional. Looking for someone with experience in getting Klarna (now kustom.co) getting to work with OpenCart 2.3.0.2. I do already have a working module, created by FooMedia (opencart.nu) long time ago. Modified later by consultants. Already Upgraded to latest Klarna KCO v3, code updated. It's also multistore compatible, have api key tabs per store and language. It has multiple features. It's not a module available on the market. There is no officially compatible OpenCart module and Kustom.co do not give support for custom stuff. When using live mode at OpenCart with live API key: Unexpected reponse HTTP status 401. Excepted HTTP status should be in 2xx range When using test mode at OpenCart with test API key: BAD_VALUE: Bad value: confirmation (#3a17ff90-fc01-4537-ad99-e759c1167a14) ServiceVersion: SNAPSHOT = Error only if using Multistore. It does not matter whether I use a live API key or a test (playground) key — all keys work perfectly on the default OpenCart store, meaning the primary store. They also work on a completely different server, as long as the store in question is the primary one. For OpenCart multistore setups, however, no API key seems to work. The error message mentioned above appears in every case. I can use the live API key K67abc or K67xdc (live keys from either old Klarna portal or new Kustom portal) for any country, but only on primary OpenCart stores — that is, the store which is installed as the main one. It doesn't matter which domain is used; it works regardless. So, clearly, the keys are not locked to a specific domain. This also applies to playground (test) API keys — but again, only on primary stores. In other words, I can use my live and test keys on both roottest.eu and web01.root.se. The same keys work on both. Every key works on both. What do they have in common? They are both primary stores. On the other hand, web02.root.se is a secondary store — a multistore managed under web01.root.se — and that's where the error occurs. When setting up OpenCart, you of course choose where the installation is to be placed — on a specific domain. After that, secondary stores can be added from within the OpenCart admin panel. These are what we refer to as multistores, and it is through them that the error messages appear. We need to find out why these error messages occur.