Attribute &1: Value &2 contains special characters

What causes this issue?

The attribute value contains special characters. This can lead to
problems during the transfer to SAP BW. Only the characters ' !"%
<(>&<)>'()*+,-./:;<(><<)>=>?_0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ' are
allowed for key figures in SAP BW.

System Response

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

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.