Characteristic &1: Reference to master inspection char. &2 was cancelled

What causes this issue?

This characteristic was unblocked. The link between the master
inspection characteristic and inspection characteristic is now broken.
There is no longer a reference to this inspection characteristic by the
master inspection characteristic. As a result the inspection
characteristic no longer appears on the where-used list for the master
inspection characteristic.
All the data from the master inspection characteristic is copied into
the inspection characteristic. You can now change the data.

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?

Error message extract from SAP system. Copyright SAP SE.