Postings already made in company code &1 with transaction FBCB

What causes this issue?

For the migration to new General Ledger Accounting, you have already
used transaction <AB>FBCB</> in company code &V1& to post data in period
0 of fiscal year &V2& in new General Ledger Accounting.
Repeat execution of balance carryforward would overwrite the
carryforward period of the fiscal year.

System Response

Processing is terminated.

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.