"Sequence not unique" and signature errors

Sequence and signature errors mean a device's running counter or its document hash chain is out of step — usually after an interrupted submission or a power/network drop mid-send.

What PI Fiscal does automatically

It detects the mismatch, re-aligns the sequence, and resubmits the pending document verbatim — keeping its original fiscal number. You normally don't need to do anything.

What you should do

1. Don't create a new invoice for the same sale — check the queue first, the document is likely already there.
2. Let the platform resubmit; watch the status change to submitted.
3. If it persists after a few minutes, open a support ticket with the device ID and the time it happened.

Prevent repeats

Stable power and connectivity on the device reduce these. Documents raised during an outage queue safely and submit in order when the link returns.