@Chetan Sharma
First, suggest starting your own thread ... your migration from 1.9.x to 2.3.x it appears to have been successful and your issue now is with something else ... mini site inside Moodle?, a SCORM package?, a whatever? ... however, be specific in description ... include what main.html is.
Your specific problem deserves it's own attention/thread ... otherwise it's buried under a topic which may/may no longer relate.
'spirit of sharing', Ken