Transaction SAD0 no longer supported from 4.0 (-> long text)

What causes this issue?

All user addresses, external addresses, and communication partner
addresses (maintained with transaction SAD0) have been converted to the
new central address management (Business Address Services) for Release
4.0.

System Response

The transaction SAD0 is no longer supported.

How to fix this error?

User addresses and their company addresses can be maintained in user
maintenance (transaction SU01). The user address can also be changed in
the SAPoffice settings.
External company addresses and contact person addresses can be
maintained with the transactions SOAD and SOCP respectively.
These transactions are in the SAPoffice menu, under Administration ->
Company addresses or Administration -> Contact person addresses.
You can access the SAPoffice menu by choosing System -> Services ->
Office, or using transaction code SOFF.
Addresses of other objects (for example, organizational units such as
plant or company code) can no longer be maintained directly, but only in
the object-specific maintenance transactions (plant addresses, for
example, in plant maintenance in the customizing transaction OX10).

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.