The variant name contains the illegal character &

What causes this issue?

You attempted to create a variant with a name containing an invalid
character. The characters "&" and "%" are not allowed in variant names.
Exception: System variants beginning with SAP& or CUS&.

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?

Correct the name.

Error message extract from SAP system. Copyright SAP SE.