Additional info key &2 &1 was determined for dangerous goods

What causes this issue?

The system determined the <DS:DE.J_7LINFOK>additional info key</>
<ZH>&V2(C)&</> <ZH>&V1&</> for dangerous goods. Non-numeric additional
info keys cannot be interpreted correctly.

System Response

All articles with a smaller additional info key are not interpreted as
dangerous goods. The additional info key 1 is used by default for
non-numeric additional info keys.

How to fix this error?

If you have maintained non-numeric additional info keys for the
recycling partner &V3&, you should change these to numeric additional
info keys.

Error message extract from SAP system. Copyright SAP SE.