External error: &1&2&3 (&4)

What causes this issue?

An error has occurred in an external system (e.g. APO). The error text
is as follows:

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

<ZH>&V1&&V2&&V3&</>
(For technical reasons, the output is cut off after 150 characters).

How to fix this error?

INCLUDE NA_SYSADMIN1

Procedure for System Administrators

An existing long text for this error message in the external system
might contain further information.
The subsequent character string contains the following data (limited to
50 characters):
Original system
Message type
Message type
Message number
The four variables
<ZH>&V4&</>

Error message extract from SAP system. Copyright SAP SE.