"internal error" with marketing events attendance

[DatFish]

I’m trying to test a custom integration option using the marketing / marketing-events API. I’ve successfully been able to add and update an event, but when I try to add a registration I get an internal error message

URL: /marketing/v3/marketing-events/attendance/{externalEventId}/{subscriberState}/email-create

where externalEventId is “123” (even I created) and subscriberState is “register”

…but I keep getting a “500” response - “internal error” - see screenshot.

Not a very helpful response if there’s something wrong with this request…

[DatFish]

I figured it out finally. I needed to add the externalAccountId as a parameter, even though this is not indicated as required (with a *) in the documentation.