&1: Long characteristics or long material not supported in CIF

What causes this issue?

MFLE: Restrictions for Classification and Variant Configuration
scenarios.
Characteristics with more than 30 characters or material number longer
than 18 characters with characteristics not supported in CIF.
Characteristics/Material number: <(>&<)>1
See SAP Note 2356739

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.