&1 invalid; provide a valid RFC connection

What causes this issue?

The RFC destination, provided as the input parameter of the transfer
method, is either invalid or does not exist.

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?

Follow these steps to provide a valid RFC destination:
Go to Customizing of Commercial Project Management -> Project Cost and
Revenue Planning -> Transfer Data -> Make Settings for Transfer Methods.
Select the transfer method used for transfer of data to MRS. For
example, the standard method for transfer to MRS is '0TRANS_METH_MRS'.
Double-click on Assign Input Fields.
Enter the correct RFC destination name in the Field Value field
corresponding to the Destination field.
Save and initiate transfer again.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.