Change server authentication mode

APPLIES TO: yesSQL Server noAzure SQL Database noAzure Synapse Analytics (SQL DW) noParallel Data Warehouse

This topic describes how to change the server authentication mode in SQL Server 2019 (15.x) by using SQL Server Management Studio or Transact-SQL. During installation, SQL Server Database Engine is set to either Windows Authentication mode or SQL Server and Windows Authentication mode. After installation, you can change the authentication mode at any time.

If Windows Authentication mode is selected during installation, the sa login is disabled and a password is assigned by setup. If you later change authentication mode to SQL Server and Windows Authentication mode, the sa login remains disabled. To use the sa login, use the ALTER LOGIN statement to enable the sa login and assign a new password. The sa login can only connect to the server by using SQL Server Authentication.

Before you begin

The sa account is a well-known SQL Server account and it is often targeted by malicious users. Do not enable the sa account unless your application requires it. It is very important that you use a strong password for the sa login.

Change authentication mode with SSMS

  1. In SQL Server Management Studio Object Explorer, right-click the server, and then click Properties.

  2. On the Security page, under Server authentication, select the new server authentication mode, and then click OK.

  3. In the SQL Server Management Studio dialog box, click OK to acknowledge the requirement to restart SQL Server.

  4. In Object Explorer, right-click your server, and then click Restart. If SQL Server Agent is running, it must also be restarted.

Enable sa login

You can enable the sa log in with SSMS or T-SQL.

Use SSMS

  1. In Object Explorer, expand Security, expand Logins, right-click sa, and then click Properties.

  2. On the General page, you might have to create and confirm a password for the sa login.

  3. On the Status page, in the Login section, click Enabled, and then click OK.

Using Transact-SQL

The following example enables the sa login and sets a new password. Replace <enterStrongPasswordHere> with a strong password before you run it.

ALTER LOGIN sa ENABLE ;  
GO  
ALTER LOGIN sa WITH PASSWORD = '<enterStrongPasswordHere>' ;  
GO  

Change authentication mode (T-SQL)

The following example changes Server Authentication from mixed mode (Windows + SQL) to Windows only.

Caution

The following example uses an extended stored procedure to modify the server registry. Serious problems might occur if you modify the registry incorrectly. These problems might require you to reinstall the operating system. Microsoft cannot guarantee that these problems can be resolved. Modify the registry at your own risk.

USE [master]
GO
EXEC xp_instance_regwrite N'HKEY_LOCAL_MACHINE', 
     N'Software\Microsoft\MSSQLServer\MSSQLServer',
     N'LoginMode', REG_DWORD, 1
GO

See also

Strong Passwords
Security Considerations for a SQL Server Installation ALTER LOGIN (Transact-SQL) Connect to SQL Server When System Administrators Are Locked Out