View field &-& (type not consistent with base field)

What causes this issue?

A data element which has a different type than the base field was
assigned to a view field.

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?

Generally view fields refer to the data elements of their base fields.
You can make sure of this in the view definition in the ABAP/4
Dictionary by deactivating the modification flag for the view fields.
If another data element should be assigned nevertheless, at least the
domain of the base field should agree with the domain of the view
field. In some cases (generated view on a matchcode ID and for base
fields to which no data element was assigned), it is sufficient if the
type and length agree, but this was not the case here.
For the corresponding field of the matchcode ID or view, enter a data
element which at least agrees in type and length with the base field or
cancel the modification flag.

Error message extract from SAP system. Copyright SAP SE.