Generation of a conversion program for table & is not allowed

What causes this issue?

Table &V1& is a cluster table and the optimized cluster technique is
active.

System Response

Process will be canceled.

How to fix this error?

Contact SAP for support.

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.