What each error actually means, what causes it, and how to check which cause is yours. Written from reading the source of the official integrations and the failures shop owners report.
OrderGuard is a free diagnostic plugin. It runs six checks against your own site and tells you, in plain language, which of these causes is yours. It asks for no API keys, contacts no external service, and writes nothing to your products or orders.
It also names the paid orders your supplier never collected, and adds up the money sitting in them. That one runs entirely on your own database.
Get the free plugin