Combination item category &/account assignment category & not defined

How to fix this error?

<GL:item_category>Item category</> &V1& and
<GL:account_assignment_category>account assignment category</> &V2& may
not be entered for the same item.
IF &[SWITCH]S4H_DOCU_CLOUD& = 'X'.
As a configuration expert, you can define the permissible combinations
of item categories and account assignment categories in the
configuration app <ZK>Manage Your Solution</> -> <ZK>Configure Your
Solution</> -> <ZK>Application Area: Sourcing and Procurement</> ->
<ZK>Sub Application Area: Operational Procurement</> -> <ZK>Account
Assignment</> -> <ZK>Define Combination of Item Categories/Account
Assignment Categories</>.

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

<ZH>Please note:</>
If you want to create a purchase order with a customer-defined
combination of item category and account assignment category, you have
to use the app <ZK>Create Purchase Order - Advanced</>. The custom
combination is not available in the app <ZK>Manage Purchase Orders</>.
ELSE.
The permissible combinations of item categories and account assignment
categories are determined in Customizing (Purchasing), transaction
<DS:TRAN.OMG0>OMG0</>.
ENDIF.

What causes this issue?

INCLUDE EINGABE_PRUEFEN_NA LANGUAGE EN

Error message extract from SAP system. Copyright SAP SE.