I have an issue when creating batch contacts - I keep getting an error 400 bad request.
My JSON is valid (as confirmed by various online tools), I have triple checked my custom properties, they all exist and are correct, but I keep getting a bad request error.
All emails are valid (since my company uses Mailgun email validation), and as far as I know, there are no special characters or anything like that in names or values.
Could this happen if for example a user already exists in my HubSpot Contacts, or will the batch create/update just update the existing contacts?
Also I have tested this on smaller batches of like 10-15 users, when I was testing and it worked fine…
Any help would be greatly appreciated!