Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error creating document instance. Cause: org.xml.sax.SAXParseException; lineNumber: 2; columnNumber: 6; Processing instruction targets matching "[xX][mM][lL]" are not allowed.
Reason for error: There is a blank line in .xml, as follows:
Solution: delete the first line and write in the top box.