The bank account already exists as a closed bank account.

What causes this issue?

The bank account you have just defined matches a bank account that
already exists in the system as a closed bank account.

System Response

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

How to fix this error?

Do either of the following:
If you want to reuse this closed bank account, you can reopen it.
If you want to create a new bank account, change one or more of the
following keys to differentiate it from the closed bank account:
Bank account number
Bank country
Bank key
Currency

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.