Every error response from the PreVOP verification API follows RFC 7807 Problem Details. The type field in the JSON body is a link to the matching page below — if you are reading this, you likely arrived here from such a link.

Machine-readable identification: use the code field in the response body (e.g. VALIDATION_FAILED), NOT the type URL. The URL format may change between versions; the code will not.

Client-side errors (4xx)

Code	HTTP	Summary
VALIDATION_FAILED	400	Your request body failed the gateway's input validation.
FORMAT_ERROR	400	EPC schema violation, typically detected upstream.
TIMESTAMP_INVALID	400	X-Request-Timestamp missing, malformed, or outside the replay window.
CLIENT_INVALID	401	Client certificate or X-Customer-ID not accepted.
CLIENT_INCONSISTENT	400/401	Credentials authenticated but do not match the request payload.
CUSTOMER_BLOCKED	403	Your customer account is not currently active.
QUOTA_EXCEEDED	429	Contracted quota (plus any extra allowance) is exhausted.

Server-side errors (5xx)

Code	HTTP	Summary
UPSTREAM_UNAVAILABLE	502	Upstream VOP provider returned an error or was unreachable.
UPSTREAM_TIMEOUT	504	Upstream VOP provider did not respond in time.
INTERNAL_ERROR	500	PreVOP-side failure. Rare; report to alseda with the X-Request-ID.

Reading an error response

Each error includes a code (machine identifier), a title (short summary), a status (HTTP code), and optionally a detail and issues[] array. Check the X-Rejected-By-Provider response header to tell gateway-side errors from upstream-side ones — relevant for several of the 4xx codes above.

Full contract: the Customer API Contract (shared with your alseda integration lead) contains the exhaustive spec; this page is the public entry point linked from every runtime error response.

Support

Email prevop-support@alseda.com with the response's X-Request-ID — that lets us correlate your failure against our logs.