No reference types are allowed in RFC

What causes this issue?

You tried to assign a refrence type to a parameter of a function module
that can be called remotely (for example containing references to
objects or fields). This 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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.