Unit of measure & not maintained for material &

What causes this issue?

You have chosen a unit of measure that does not yet exist in the
material master record.

How to fix this error?

Create the unit of measure &V1& as an alternative unit of measure in
the material master reocrd.

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

Error message extract from SAP system. Copyright SAP SE.