Replacement &4 of component &1 is of an unsupported type.

What causes this issue?

The replacement &V4& of component &V1& in structure &V2& of data class
&V3& is of a type that is not supported.

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?

Use transaction SM30 to choose a different placeholder or change the
placeholder type to a character-type data type.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.