Import redmine 2.3.2 sql data into redmine 2.6 issue

Has anyone try to test redmine 2.6? I installed the latest bitnami-redmine 2.6, and export my sql data from current redmine 2.3.2 env., then import the sql through phymyadmin into the mysql database, then the thin redmine service stopped, is there big change from redmine 2.3.2 to 2.6, if sql not compatiable, then we cannot update to the latest redmine version....