Hi,
I hope you are looking for this.
Best practices for upgrading to Symantec Endpoint Protection 12.1.2
http://www.symantec.com/business/support/index?pag...
https://www-secure.symantec.com/connect/articles/s...
http://www.symantec.com/business/support/index?page=content&id=TECH197426&profileURL=https%3A%2F%2Fsymaccount-profile.symantec.com%2FSSO%2Findex.jsp%3FssoID%3D13641969182859KQ64RuKsQHu78Rz0VOPDC2xjDFBn6SH9azvm
http://www.symantec.com/business/support/index?page=content&id=TECH163602&profileURL=https%3A%2F%2Fsymaccount-profile.symantec.com%2FSSO%2Findex.jsp%3FssoID%3D13641969181669pbtg34is5hfPm494MHLK9b5GcuRMi3K69iut