Quantities cannot be converted for the material &

What causes this issue?

The quantity or quantities could not be converted from one unit of
measure to another because the specified alternative unit of measure
cannot be converted to the base unit of measure.

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?

Specify the conversion factors for the alternative unit of measure in
the material master record &V1&.
Industry
<DS:TRAN.MM02>Proceed</>
Retail
<DS:TRAN.MM42>Proceed</>

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.