Hi Vijaya, I had a similar issue.
In my case one field of the one table of the RFC Function returned text values that contains invalid XML characters. This issue just happens when the RFC function returns invalid XML characters, like a text that the user have imported from another program (microsoft excel) to the SAP tables.
A test that you can do to be sure that we are talking about the same issue is that you can debug your RFC and clear the texts field values, the MII execution should work.
So, considering that your invalid character is still there, the RFC execution were made successfully in the ABAP side, but when the RFC execution finishes, on the MII side an exception is throwed.
I think that it happens because the java parser try to convert the RFC returned content to a XML content, and that character can not handled as an XML content.
So, the solution that we found was in the ABAP side remove any invalid XML characters before leave the RFC to return that content to MII side. We considered as an invalid character anything that was not "a,b,c...z" "1,2,3...0" ",.-" (your ABAP consultant will know how to do it).
