Connection object &1 is not consistent in database

What causes this issue?

The IS-U connection object is saved to the database as a special
functional location (PM).
Certain consistency rules apply to connection objects. The specified
connection object is not consistent with these rules.
There is probably a data inconsistency between the IFLOT and EHAUISU
tables.

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.