General error codes
Most error codes are universal and are often caused by the issuer not allowing the transaction to go through
Error codes starting with certain numbers have a general meaning that falls into these different categories.
2 means the status is "uncertain". This will usually evolve to a final status.
3 the transaction is declined by the acquirer or blocked by your fraud detection module.
4 means the transaction is declined. It could be only a temporary technical issue. Please retry a little bit later.
5 means a validation/configuration error (e.g. currency not allowed on your account).