M8 108
Invoice already entered — duplicate invoice check
MIRO or an inbound invoice raises a duplicate-invoice warning/error because SAP finds an existing invoice with matching duplicate-check criteria.
Quick answer
- Most likely cause
- The supplier invoice was already posted.
- Check first
- Supplier invoice reference and invoice date.
- First resolution step
- Confirm whether an accounting document already exists before retrying.
Likely root causes
- The supplier invoice was already posted.
- Reference, invoice date, amount or company-code data matches an existing invoice closely enough to trigger duplicate checking.
- An interface resent the same invoice after a timeout or acknowledgement failure.
What to inspect
- Supplier invoice reference and invoice date.
- MIR4/MIRO document search for an existing posting.
- Vendor/company-code duplicate-invoice-check settings.
- Interface retry/idempotency logs if the invoice arrived electronically.
Resolution path
- Confirm whether an accounting document already exists before retrying.
- If this is a true duplicate, stop the repost and correct the upstream resend process.
- If the document is genuinely different, correct the reference/master-data fields that caused the false match according to policy.
- Retest without disabling duplicate controls globally.
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