Error during Gross/Net volume UoM substitution. See long text.

What causes this issue?

During Gross/Net volume UoM substitution an error has occurred
(Function module GROSS_NET_UNIT_CHECK).

System Response

The specified unit of measure '&V1&' is not a volume unit of measure.
Gross/Net volume UoM substitution is only designed for volume unit of
measures. Therefore the call of function module GROSS_NET_UNIT_CHECK
does not make sense.

How to fix this error?

The following explanation concerns customizing of Gross/net volume unit
of measure substitution in the R/3 system. If you do not have detailed
knowledge in that area or if you do not have the appropriate
authorizations, contact your system administrator.
Check from where the function module GROSS_NET_UNIT_CHECK is called.
The calling modularization unit should ensure:
that the function module is only called for volume unit of measures
or that it handles the exception 'NO_VOLUME_UNIT' of the function
module correctly.

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.