Subsequent IDOC already processed; expected: &; current: &

What causes this issue?

Sequencing in order was activated for the party. The current IDoc has
been given the counter &v2&; however, IDocs with a higher counter number
have already been processed. Next counter expected is &v1&.

System Response

It is not possible to process the IDoc.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.