Aggregate Error

This is the source code:
person/firstName/text()
${in.header.breadcrumbId}
;convertBodyTo type="java.lang.String"/;
corrId
The error which I'm getting is " Error during type conversion from type:
java.lang.String to the required type: java.lang.Integer with value due
java.lang.NumberFormatException: For input string: "" "In route 2 target
folder there are 2 files called msg1, msg2 with some name.Please help to
resolve this error.