Partner function &1 cannot be used by suppliers in account group &2

What causes this issue?

Partner function &V1& is assigned to your vendor at level &V3&. This
function is entered by the vendor.
However, this partner function is not allowed for vendors in account
group &V2& which is to be assigned.

System Response

A change of account group is not permitted.

How to fix this error?

Please change the partner functions for the account group in
Customizing.

Error message extract from SAP system. Copyright SAP SE.