Standard value key: Parameter & has different dimension than &

What causes this issue?

You want to change the standard value key for a work center. However
this work center is already used. That means that the standard values
that were specified by the old standard value keys can already be
maintained.
A standard value is defined via a parameter ID. Using the changed
standard value key a new standard value is defined via the parameter
ID &V1&.
This standard value has a different dimension and a different unit of
measure from the standard value which was specified using the old
standard value key via the parameter ID &V2&.

How to fix this error?

Using the where-used list select the routings in which the work
center is already used. Correct the standard values if necessary.

Error message extract from SAP system. Copyright SAP SE.