Ledger group missing for company code &1, accounting principle &2

What causes this issue?

In the Customizing settings for <LS>Multiple Accounting Principles in
Controlling (COGM)</> for company code &V1& and accounting principle
&V2&, the ledger group determination is set to <LS>Explicit Assignment
</>. However, the field <LS>Ledger Group (FI)</> is empty.

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?

Check Customizing activity
<DS:SIMG.V_FCML_MLCO_COFI>Set Up Integration with G/L for Multiple
Accounting Principles in Controlling (COGM)</>.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.