---
title: "Change Server Authentication Mode | Microsoft Docs"
ms.custom: ""
ms.date: "02/18/2020"
ms.prod: sql
ms.prod_service: high-availability
ms.reviewer: ""
ms.technology: configuration
ms.topic: conceptual
helpviewer_keywords: 
  - "sa account"
  - "authentication [SQL Server], changing modes"
  - "server authentication mode [SQL Server]"
  - "modifying server authentication mode"
ms.assetid: 79babcf8-19fd-4495-b8eb-453dc575cac0
author: MikeRayMSFT
ms.author: mikeray
---

# Change server authentication mode

[!INCLUDE[appliesto-ss-xxxx-xxxx-xxx-md](../../includes/appliesto-ss-xxxx-xxxx-xxx-md.md)]
This topic describes how to change the server authentication mode in [!INCLUDE[ssCurrent](../../includes/sscurrent-md.md)] by using [!INCLUDE[ssManStudioFull](../../includes/ssmanstudiofull-md.md)] or [!INCLUDE[tsql](../../includes/tsql-md.md)]. During installation, [!INCLUDE[ssDEnoversion](../../includes/ssdenoversion-md.md)] 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 [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Authentication.

## Before you begin

The sa account is a well-known [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] 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 [!INCLUDE[ssManStudioFull](../../includes/ssmanstudiofull-md.md)] 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 [!INCLUDE[ssManStudioFull](../../includes/ssmanstudiofull-md.md)] dialog box, click **OK** to acknowledge the requirement to restart [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)].

4. In Object Explorer, right-click your server, and then click **Restart**. If [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] 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.

```sql  
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.

```sql
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](../../relational-databases/security/strong-passwords.md)   
 [Security Considerations for a SQL Server Installation](../../sql-server/install/security-considerations-for-a-sql-server-installation.md)
 [ALTER LOGIN &#40;Transact-SQL&#41;](../../t-sql/statements/alter-login-transact-sql.md)
 [Connect to SQL Server When System Administrators Are Locked Out](../../database-engine/configure-windows/connect-to-sql-server-when-system-administrators-are-locked-out.md)