Error: & & with variables & &.

What causes this issue?

During processing, error &V2& occurred. The error is in message area
&V1& and has the variables &V3& &V4&.

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?

For a more detailed analysis of the error, see the long text for error
message &V2&. To do so, use the transaction <DS:TRAN.SE91>display
messages</>.

Error message extract from SAP system. Copyright SAP SE.