Obligatory target element could not be created

What causes this issue?

A field that is indicated in Customizing as being obligatory could not
be created, because an element required for creation could not be
found, as defined, in the source container.
Following target element is affected: '&V1&' / key field: '&V2&'
Following source element is missing: '&V3&'

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?

Transfer all obligatory source container fields.

Error message extract from SAP system. Copyright SAP SE.