validation_failed

What it means

The body was read, but a field is missing, has the wrong type, or has a value we do not accept. error.message lists each field and what is wrong with it.

Why it happens

• A required field is missing or misspelled (origin_url, not originUrl).
• A value is out of range: limit above 100, metadata above 4 KB, an unknown mode or apex_redirect.
• An action does not apply in the current state, for example POST /verify on a test domain or on a domain that is rate-limited by the certificate authority.

What to do

1. Read error.message: it names the field.
2. Compare the body with the OpenAPI document.
3. Unknown fields in a domain body are rejected rather than ignored, so a typo is caught here.