Characteristic &1 has the special data type &2

What causes this issue?

The IPC does not fully support the entry and display of values with data
type CURRENCY.

System Response

The characteristic is copied into the knowledge base, but is only
treated as a numeric characteristic.

How to fix this error?

If you are using an older version of IPC Release 3.0, check also SAP
Note 451297.

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.