User &1 cannot log on to this client.

What causes this issue?

This client was originally a central system in a Central User
Administration (CUA) or was created as a copy of a central system.
User &V1& only existed there for administrative purposes, and therefore
had no system assignment for this client. The user therefore could not
log on to this client.

System Response

User &V1& is still not permitted to log on.
Changes to this user therefore have no effect.

How to fix this error?

Our recommendation for how to handle this warning depends on the future
purpose of this client.
If you are going to use the client as a CUA central system again in the
near future, you can ignore this warning, since it will not be shown in
a CUA central system.
However, if you are going to continue to use this client as a standalone
client or as a child system of a CUA, you can delete users of this type.
Use the report RSDELCUA to delete these users.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.