Error Code NACK

NACK - ISO 20022 Negative Acknowledgement

Read a plain-English explanation of NACK responses, why they happen, and how to fix the underlying MT or MX issue fast.

Why this rejection happened

The receiving bank or gateway rejected the payload after a structural, semantic, or business-rule check failed, leaving the sender with a negative acknowledgement.

How to fix it

Inspect the rejection reason in the NACK payload and compare the message structure against the relevant MX schema such as pacs.008 or pacs.009. Fix the invalid field or mapping before resending.

Common trigger points

pacs.008 negative acknowledgement
schema validation rejection
message-level reject

Resolve NACK issues fast

Use the live SwiftMX Bridge converter to transform your MT instruction into a compliant MX payload and fix the underlying NACK problem before it blocks settlement.

Open the live converter