This indicates that the password is incorrect. Error: 18456, Severity: 14, State: 8. When SQL Server is installed using Windows Authentication mode and is later changed to SQL Server and Windows Authentication mode, the sa login is initially disabled.
The error code 18456 in the SQL server means that the server could not authenticate the connection and this can happen if the TCP/IP protocol required to access the database on a network is disabled in the Server Configuration Manager. In this context, enabling the TCP/IP in the SQL Server Configuration Manager may solve the problem.
SQL Server may display the confusing code 18456 if the SQL Server authentication method does not match the correct location (for example, you are trying to access the Internet with SQL Server authentication while the core server is configured not to use Windows authentication) . In this case, replacing the SQL Server authentication method may solve the problem.
In SSMS, right-click the server name at the top of the Object Explorer window and select Restart to view the new authentication mode options. In the example above, Windows Authentication Type was the only mode configured, but error 18456 occurred because her user “sa” is an SQL statement and SQL Server Authentication is definitely not allowed.
If Windows Authentication is working correctly, you should open the SQL Instance Properties and go to the Security tab. Change the server authentication process to SQL Server and Windows authentication mode (this is a mixed certification mode).
How do I fix Login failed for Microsoft SQL Server Error 18456 Step by add SQL administrator to SQL Management Studio?
Troubleshooting Microsoft SQL Server error 18456
- Step 1: Remote desktop connection.
- Complete Step 2: Administering Microsoft SQL Server.
- Step 3: Authenticate in server mode.
- Step 4: Restart the SQL service.
- Step 5: Check the permissions of the SQL user. Step 6:
- The step of adding a user to the database.
How do I fix the login failed for Microsoft SQL Server Error 18456?
Troubleshooting Microsoft Server SQL Error 18456
How do I fix the login failed for user sa Microsoft SQL Server Error 18456?
Troubleshooting Microsoft SQL Server error 18456
- Step 1: Connect using Remote Desktop.
- Step 2: Start Microsoft Server SQL Management.
- Step 3: Check server mode authentication.
- Step 4: Restart the SQL service on the computer.
- Step 5: Check the permissions of the SQL user.
- Step 6: Assign users to the database.
How do I fix the Login failed for user sa Microsoft SQL Server Error 18456?
Troubleshooting Microsoft SQL Server error 18456
- Step 1: Remote desktop connection.
- Step 2: Start Microsoft SQL Server Management.
- Step 3: Check the server’s authentication mode.
- Step 4: Restart any SQL service.
- Step 5: Check the permissions of the SQL user.
- Step 6: Assign users to the database.

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