Another morning wasted on this. The API is returning a 400 Bad Request when trying to update a record via the /contacts/update endpoint. The payload looks fine and the CONTACT_ID is definitely valid.
This killed our automated lead injection for two hours. Tried stripping the body down to just one field to see if it’s a payload size issue, but it still fails.
{
"contactId": "12345-abcde",
"fields": {
"custom_field_1": "TestValue"
}
}
Tried hitting the endpoint through Postman and the same error pops up. Everything is configured for the correct TENANT_ID.