Debug:
I reported this error when I was a beginner of mybatis

Error building SqlSession.

Cause: org.apache.ibatis.builder.BuilderException: Error creating do

Caused by: org.xml.sax.SAXParseException; lineNumber: 2; columnNumber: 6; Processing instruction targets matching ‘[XX] [mm] [ll]’ are not allowed.

Finally, it is found that one line is left blank at the beginning of the SQL mapping file, but it is required that one line cannot be left blank. Just remove the blank line