No MM purchasing group specified for TM purchasing group: &1

What causes this issue?

You attempted to save and transfer a freight settlement document from
Transportation Management system to S/4 Hana system. However, the system
cannot post the document because some key information is missing. You
specified a purchasing group in Transportation Management (TM) in the
document, but you have not specified a purchasing group for the purchase
order and service entry sheet. The system needs this information to map
to the correct information in MM. The system cannot create a purchase
order and SES.

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?

Contact your system administrator.

Procedure for System Administrators

You must do one of the following:
In SAP Transportation Management System, enter the MM purchasing group
for the relevant TM purchasing organization in transaction PPOME -> Org.
Data -> BSD Org. Unit.
In your S/4 Hana system, enter a purchasing document type, material
group, plant, and purchasing group for the relevant freight settlement
document type in Customizing for Transportation Management under
<LS>Settlement</> -> <LS>Freight Settlement </>-> <LS>Integration for
Settlement Posting </>-> <LS>Assign Purchasing Information for Posting
</>.
When SAP TM sends the XML message for the freight settlement document,
the MM purchasing group if maintained for the TM purchase group in the
field BSD Org Unit is sent. When the S/4 HANA system receives such XML
the system uses this MM purchase group in the XML message. Otherwise the
system checks the settings in the <LS>Assign Purchasing Information for
Posting </>Customizing activity.

Error message extract from SAP system. Copyright SAP SE.