994 Official

Duplicate Record

A unique constraint violation — the record already exists. Documented for the OSCU path. On the VSCU path the same situation returns 899 instead — verified against the live VSDC 2.0.6 sandbox JAR (2026-07-06).

Likely Causes

Invoice number already used for this branch
Duplicate transaction submitted after a timeout retry
Offline queue replay submitting an already-processed invoice

Fix

Invoice numbers must be sequential integers and can never be reused even after cancellation. On OSCU retry and offline replay, treat 994 as an idempotent success — the invoice was already registered; do not raise an exception. On the VSCU JAR path, do not wait for a 994 that never comes: a duplicate-invoice replay returns 899 with a generic client-error message — confirm via the select endpoint or receipt-counter arithmetic before treating the replay as failed.

Gotcha

If a retry of a timed-out submission returns 994 (OSCU) or 899 (VSCU), the original submission likely succeeded — KRA consumes the receipt counter even when the HTTP response is lost to a client timeout. Check invoice status via the corresponding select endpoint before treating this as a hard failure.

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