This error message will be presented when attempting to file a corporation tax return or a set of accounts online if you have multiple entries present in the financial statements for directors loan account (one appearing in the debtors note and one appearing in the creditors note).
The easiest way to resolve this error message is to open the accounting period within Accounts Production and disable the breakdown of the debtors note. To do this go to Notes > Edit Notes > Locate the Debtors note and un-tick the box for Show a breakdown of Debtors. Once you have saved this change, for consistency you may want to disable the creditors breakdown too however you can leave this active if you choose.
Once the necessary change has taken place, you can choose to re-file the accounts/tax return as required. Please note, if you have attached the accounts to the corporation tax return, you will have to remove and re-attach the accounts before re-filing.