What is a UPO in KSeF?

UPO (Urzędowe Poświadczenie Odbioru) is the official acceptance confirmation issued by KSeF once an invoice is accepted. It is the Polish e-invoicing equivalent of a Peppol MLR.

Why does 21178 fire even though I just submitted the invoice?

UPO generation is asynchronous. You must first poll invoice status until it reaches Accepted (200); only then is the UPO available for retrieval.

Can I request a UPO for a rejected invoice?

No. UPOs are issued only for accepted invoices. A rejection has its own error payload with the reason for rejection.

What is the correct polling pattern?

Exponential back-off starting at 2 seconds, capped at 60 seconds, for up to 5 minutes. If you still see 21178 after 5 minutes, escalate — the invoice may have failed silently.

Error codes · KSeF 2.0 · Poland

KSEF-21178Partly

KSeF UPO (Urzędowe Poświadczenie Odbioru) not found

This is the rejection, word for word: „[KSEF-21178] You requested the UPO (Urzędowe Poświadczenie Odbioru — the official acceptance confirmation) for a KSeF invoice, but the system could not find a UPO matching the provided criteria. Either the invoice has not yet been assigned a UPO, or the search parameters (referenceNumber, KSeF number, sessionReferenceNumber) do not identify a valid invoice.“

The 21178 code surfaces on GET /invoices/{ksefNumber}/upo and related UPO retrieval endpoints. Common root causes: the invoice is still in processing state (UPO not yet generated), the KSeF number in the request path is malformed, or the requesting entity does not have permission to see the UPO for that invoice. The response payload uses HTTP 404 with body code 21178.

What to have readyThe correct figures from your bookkeeping; we show you which field is affected.

What we doVerify the invoice reached terminal status before requesting UPO. Check the KSeF number format and the requesting user permissions.

Choose the rejected invoiceor drop it here

XRechnung XML or ZUGFeRD PDF. Checking is free · corrected file €1.90 · the first every 30 days is free · no sign-up.

What the finding looks likeExample

FindingNeeds your check · KSEF-21178

From youThe correct figures

ThenChecked again

ProofSHA-256 and /verify link after the check

Often appears together with

KSEF-21180KSeF session status does not allow this operation KSEF-21181Sellers are not identical for all invoices in a KSeF batch KSEF-21182KSeF concurrent export limit reached