The processing instruction target matching "[xX][mM][lL]" is not allowed

This message is related to xml directly.This is actually related to xml parsing .Technically id  SAX Parse exception occur then we will see this message . This exception will occur if there is any black space of line in the very beginning of the xml message , means before the line bellow :

                   <?xml version = "1.0" encoding = "utf-8" ?>  

Simple problem , simple solution just remove the black line or space in start of xml message .