# 2026-10-04 — Validation messages include field paths (improvement · API)

> Rejected requests name each invalid field in the message, including fields inside nested objects.

The `message` on a `400 VALIDATION_ERROR` now prefixes each schema issue with
its field path. A count above 20, for example, returns
`count: Too big: expected number to be <=20.` Nested fields use paths such as
`inputs[0].source.url`.

The response still includes `issues` with separate `path` and `message`
values. Use `code` and `issues[].path` when handling errors in code, since the
message wording can change. Unknown model IDs still suggest the closest ID.
See [validation errors](/docs/api-reference/errors#validation-errors).

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