User &1 was automatically excluded from the synchronization

What causes this issue?

An object was automatically excluded from the synchronization.
There are two possible reasons for this message:
During the synchronization of users, all objects with the names SAP*,
DDIC, and EARLYWATCH are always implicitly excluded from the s
ynchronization.
During the synchronization, the system found objects whose names did not
follow the applicable conventions in each case, for example, user names
that were too long during the user synchronization.

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?

Change the affected objects as required or use the selection criteria to
explicitly exclude them from the synchronization.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.