Item category &1 is missing (obligatory in accounting transaction &2/&3)

What causes this issue?

INCLUDE GLT2_GENERAL_1 OBJECT DOKU ID TX
INCLUDE GLT2_GENERAL_3 OBJECT DOKU ID TX
Item category &V1& could not be derived from a document line item. This
item category is however defined as obligatory in accounting
transaction &V2&, variant &V3&.

System Response

INCLUDE GLT2_GENERAL_6 OBJECT DOKU ID TX

How to fix this error?

INCLUDE GLT2_GENERAL_2 OBJECT DOKU ID TX

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.