i need to install frappe & erpnext version 7 in ubuntu for production purpose.
why not the latest version?
we have already done our development in erpnext 7 version.
You are doing too little and expecting too much. I see you have opened another thread where @netchampfaris has kindly replied how to do this(Help to install erpnext 7 version). You haven’t come back with an answer for his question. I would suggest you to upgrade your OS first and then upgrade your app to latest version.