Last Updated: 01.06.2019
To decrypt objects for SQL Server 2005 and later, a Dedicated Administrator Connection (DAC) needs to be established to the SQL Server database. This requires a user with system administrator rights to setup the machine prior to establishing the connection.
For more information about the SQL DAC, please see:
To conserve resources, SQL Server Express edition does not have the DAC port enabled by default. This can be turned on by starting the service with the trace flag 7806 option.
To set the trace flag, first open the SQL Server Configuration Manager.
Click on the SQL Server Services item in the tree.
Right-click on the SQL Server Service that you would like to enable the trace flag for. Select Properties.
Once the properties dialog is displayed, click the Advanced tab.
Find the Startup Parameters item in the list. Add -T 7806; to the very beginning of the parameter list.
Click OK and restart the SQL Server.
No configuration is necessary for local machine access except you must use a login that is a member of the sysadmin role. To enable the DAC connection from a remote machine, use the SQL Server Surface Area Configuration tool or run the following script from SSMS.
exec sp_configure 'remote admin connections', 1;