Supplier &1 is regular supplier for material &2

What causes this issue?

Supplier &V1& has been defined as the regular supplier for material &V2&
in the info record.
However, you wish to procure the material from a different supplier.

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?

INCLUDE NA_T160M LANGUAGE EN

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.