Please check bank statements before you edit key attributes.

What causes this issue?

You have made changes to one or more of the following attributes of a
bank account:
Bank account number
Bank key
Bank country
Bank account currency
IBAN

System Response

If bank statements have been created but not yet posted for this bank
account, after the change is saved, you can no longer process these bank
statements because one or more key attributes have been changed.

How to fix this error?

Please check whether bank statements have been created for this bank
account before you make changes to any of the key attributes.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.