e-Faktura API

Errors

Every error is application/problem+json (RFC 9457) except POST /v1/oauth/token, which uses plain OAuth 2.0 error JSON.

{
  "type": "https://developer.merot.com/efaktura/errors#validation_failed",
  "title": "Validation failed",
  "status": 422,
  "detail": "One or more fields failed UJP validation.",
  "instance": "req_01J9Z5C6D7E8F9G0H1J2K3",
  "code": "validation_failed",
  "errors": [
    { "path": "lines[2].taxIndicator", "message": "Unknown tax indicator for document type 100.", "codebook": "tax-indicators" }
  ]
}

instance is the request id — also echoed in the X-Request-Id response header; include it when contacting support.

Codes

Code	Status	Meaning
`unauthenticated`	401	Missing, malformed or expired credentials.
`key_revoked`	401	The API key has been revoked.
`insufficient_scope`	403	The key/token lacks a required scope.
`company_not_allowed`	403	The company isn’t in this key’s allow-list.
`environment_mismatch`	403	A sandbox key touched a production resource, or vice versa.
`production_not_enabled`	403	The account has no active production plan yet.
`company_required`	400	`X-Company-Id` is required (the principal has more than one company).
`idempotency_key_required`	400	A write is missing its `Idempotency-Key` header.
`idempotency_conflict`	409	The same key was reused with a different request body.
`idempotency_in_progress`	409	A request with this key is still being processed.
`client_reference_conflict`	409	The same `clientReference` was reused with a different body.
`period_closed`	409	Storno/correction blocked — the annual account is filed for that year.
`decision_deadline_passed`	409	The inbox accept/reject deadline has passed.
`signature_expired`	410	The signing request expired before a signature arrived.
`signature_invalid` / `payload_mismatch` / `certificate_mismatch`	422	The submitted signature failed verification.
`validation_failed`	422	Field-level validation errors, or `totals_mismatch` for a totals mismatch.
`pdf_not_ready`	409	The document hasn’t settled at UJP yet.
`rate_limited`	429	Too many requests — see Rate limits.
`not_found`	404	No such resource for this company.
`ujp_unavailable`	503	The synchronous UJP registry pre-flight (on company creation) timed out.

UJP-sourced errors

Where a validation error comes directly from a UJP codebook rule, errors[].codebook names the codebook, so you can look the value up yourself — Merot never renames or reinterprets UJP’s own codes.