Mollie - mollie_client.settlements.get with a real bank reference like 02893031.2309.10 raised IdentifierError: Invalid settlement ID, because the client-side bank reference regex was too narrow for real-world references (it did not allow 8-digit merchant IDs, which Mollie now issues).
## The fix
If settlements.get raises IdentifierError on a real bank reference such as 02893031.2309.10, your client version validates references against an outdated regex that assumed short merchant IDs. Mollie's bank references are merchant ID (padded to a fixed width, now up to 8 digits) dot year-month dot a 2-digit sequence, e.g. 02893031.2309.10. Upgrade mollie-api-python to 3.6.0 or later, where the validation was widened to accept 4+ leading digits and the maintainer confirmed the fix. You do not need to change your code; the same settlements.get call works once the client stops rejecting the reference.
Thread: gh:mollie/mollie-api-python#335