Customer-specific data were not saved due to error &2 &3 (see long text!)

What causes this issue?

While saving the customer-specific data of the business partner the
following error occurred:
<ZH>&V1&</>
<ZH>&V2& &V3&</>
The business partner was created/changed, the corresponding customer was
not created/changed.
Background
In your system<(>,<)> the so-called post processing office (PPO) is
active. The update of the customer-specific data is delayed (occurs
technically "on commit"), while all non-customer-specific business
partner data are updated directly after pressing the save button. Due to
technical reasons a "normal" error message is not possible any more
during "COMMIT WORK" processing. Because of this errors that occur
during processing of customer-specific data are saved in PPO and the
corresponding customer-specific database tables are not updated. This
leads to the situation that pure customer-specific fields in transaction
BP are empty after saving, although they had been filled with values
before pressing the save button.

System Response

Certain customer-specific fields in transaction BP are empty after
saving, although they had been filled with values before.

How to fix this error?

Correct your entries according to the error message mentioned above
(also available in the message short text in brackets) and save the
business partner again. If needed contact your system administrator.

Procedure for System Administrators

You can get further details related to the error directly in PPO. For
accessing PPO start transaction MDS_PPO2 and enter the corresponding
date on which the error occurred in field "Technical Creation Date". The
concerned business partner should then be available in the result list.

Error message extract from SAP system. Copyright SAP SE.