No valid communication assembly selected.

What causes this issue?

Assign und Remove is not working if you select "*" as Communication
Assembly.

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?

You can assign or unassign a Remote Function Module<(>,<)> only if you
select a specific Communication Assembly.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.