Caution: actual data exists. Reconstruct assigned values

What causes this issue?

You have made changes to a master data hierarchy (funds
center/commitment item) to which you have already made postings.

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?

Start the program to reconstruct the assgined values to ensure that
availability control can continue to identify excessive funds
assignments within the new hierarchy.

Error message extract from SAP system. Copyright SAP SE.