Document cannot be split; see long text

What causes this issue?

You are posting an invoice with a down payment clearing from Logistics
invoice verification. As new General Ledger Accounting has been
activated in your system with document splitting, the down payment
clearing needs to be split on the basis of the invoice items. To ensure
that document splitting is performed correctly in this case, you need to
assign a special logical transaction to the invoice document. Since this
assignment has not been made, the system terminates the posting process.

System Response

The document cannot be posted.

How to fix this error?

This is a system error. Inform your system administrator.

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.