RUNTIME EXCEPTION ERROR

hi friends

i am doing the file to idoc scenario. in that I am getting the runtime exception as

During the application mapping com/sap/xi/tf/_mm_file_idoc_new2_ a com.sap.aii.utilxi.misc.api.BaseRuntimeException was thrown: Fatal Error: com.sap.engine.lib.xml.parser.Parser~</

what is the solution of this error