How to fix missing_param (HTTP 400)
A required query parameter is absent. The message names it.
What the API returns
{
"error": {
"code": "missing_param",
"message": "lat and lon are required",
"request_id": "770372810e5f2a70"
}
}Why it happens
- Sending birth details under birth.* to a chart endpoint, which reads unprefixed date, time, tz, lat, lon (or the reverse on transit endpoints, which read birth.* for the chart and date/tz for the moment).
- Sending lat without lon; they are validated as a pair.
- A parameter name typo (timezone instead of tz, latitude instead of lat).
How to fix it
- Open the endpoint's reference page: its parameter table marks exactly which names are required, verified by calling the API.
- Copy the page's example request and change values one at a time.
Should your code retry?
No. The request is deterministically rejected; fix the key, IP or parameters and send it again.
See all codes on the troubleshooting index and the error envelope on Errors. Still stuck? Email [email protected] with the request_id.