No supplier could be determined for material &1

What causes this issue?

In determining the source of supply for material &V1& and the current
organization level, the system could not find a vendor. The supply
source key for the material is '&V2&'.

System Response

A price calculation is not possible for the current item.

How to fix this error?

Check the material master data and make sure the supply source key is
correct (basis data view, logistics view):
<DS:TRAN.MM43>Display material master data</>.
If you plan to procure the material externally, check if a purchasing
info record exists for material &V1& and the current plant (reference
plant) &V3& (<DS:TRAN.ME1M>Display list of information records</>).
If purchasing info records exist for the material, check the following:
Do purchasing info records exist for the purchasing organization to
which the plant belongs? If the purchasing organization refers to
another purchasing organization, check if the data referenced also
includes purchasing info records.
Is the price determination date of the price calculation within the
delivery period displayed in the general data of the purchasing info
records?
Does the indicator 'Conditions at plant level' (maintained in the
'Purchasing/distribution' view of the plant master data) possibly
exclude any information records found?
Is the current plant (reference plant) &V3& assigned to a supply region
which is not supplied by the vendor found? If so, enter the desired
vendor on the selection screen of the sales price calculation for the
current item. this will allow you to calculate the sales price
nonetheless.
If no valid purchasing info records exists, create the required
purchasing data for material &V1& in material maintenance.
If you are planning on procuring the material externally, check the
settings required for two-step price calculations (see the online
documentation):
The following must be maintained:
Supplying distribution chain in 'Distribution chain for plant' view in
the master data of the supplying plant in question.
Sales area data fort the supplying distribution chain in the customer
master data of the receiving plant (reference plant).
Supply plant in the master data of the receiving plant (reference
plant).
Please note that material master data must be maintained both for the
supplying plant and for the receiving plant (reference plant). See the
logistics views involved.
Go to the following steps to check master data and Customizing:

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

<DS:TRAS.WB03>Display plant</>
<DS:TRAN.MK03>Display vendor</>
<DS:SIMG.SIMG_CFMENUSAPCOMKJ>Reference purchasing organization</>

Error message extract from SAP system. Copyright SAP SE.