Mediation(.mfc) file could not open using Websphere Integeration Developer aka WID

"Unable to create this part due to an internal error,Reason for the failure: An unexcpected exception was thrown" This was the error i got when i opened my mediation flow in WID. I didn't have clue searched and found nothing. Then started looking seriously into the error. One of my collegue got the same error earlier and he solved it by taking previous version from reposirty, he too started getting the same error.The error said Java.lang.NullPointerException at com.ibm.wbit.sib.mediation.flow.ui.tray.editparts.ReferencePartnerTrayEditPart.getModuleChildren(Unknown Source).

Look at this error "ReferencePartner" that is the clue. We saw a pattern here and found something. It seems that the other collegue deleted the an interface. The deleted interface was having a reference in mediation flow. So when iam trying to open i started getting the above error. I manually created the interface and did a clean build. It worked we are able to open the mediation flow. So here is the thumb rule guys if you have decided to delete any interface check whether it has been used in some other components/module. In case if its mediation be carefull, check the reference partner. If its there delete it from your mediation module and go ahead with your final deletion