we are going to upgrade from SQL server 2012 Standard edition to SQL Server 2016 Enterprise edition. we can't have a downtime more than 30 mins .The new SQL server will use always on availably group 1 primary and 2 read-only secondaries . I am looking for the fastest way to do this upgrade.
I am thinking of creating mirroring between the old server and new primary server , then shut down the application update the connection string , fail over the DB to the new server, stop mirroring, start the application. After the application is up, start in configuring the Availability group.
IS this a correct way to use