Migrating from Database Mirroring to Always On Availability Groups
In version 14.00.3049.1 of Microsoft SQL Server Enterprise Edition, Always On Availability Groups (AGs) are enabled by default.
To migrate from Database Mirroring (DBM) to AGs, first check your version. If you are using a DB instance with a version prior to Enterprise Edition 13.00.5216.0, modify the instance to patch it to 13.00.5216.0 or later. If you are using a DB instance with a version prior to Enterprise Edition 14.00.3049.1, modify the instance to patch it to 14.00.3049.1 or later.
If you want to upgrade a mirrored DB instance to use AGs, run the upgrade first, modify the instance to remove Multi-AZ, and then modify it again to add Multi-AZ. This converts your instance to use Always On AGs.