### Answer The error "request/body must NOT be valid" typically occurs when you're mixing pagination methods incorrectly. [(1) ]() [(2) ]() When using

pagination_key

, you should not include

skip

in your request body. The

pagination_key

is an opaque cursor from a previous response that handles pagination automatically. Your first request works because you're likely using

limit

and

skip

(or just

limit

) . But on subsequent requests, if you're including both

pagination_key

and

skip

, this creates a conflict that triggers the 400 error. Solution: When looping through pagination in n8n, structure your requests like this: First request:

json
{
  "limit": 50
}

Subsequent requests (using the pagination_key from previous response) :

json
{
  "limit": 50,
  "pagination_key": "{{previous_response.pagination_key}}"
}

Remove any

skip

parameter when using

pagination_key

. The pagination key already encodes the position in your result set.

​ To learn more, see the sources I considered: [[1] List Calls](https://docs.retellai.com/api-references/list-calls) [[2] List Chats](https://docs.retellai.com/api-references/list-chats) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.