How To Fix SQL Server Error 18456: Here Is The Solution!

If SQL Server login fails with an error 18456, then this could have happened due to various reasons. May be, the login details entered are correct but there aren’t appropriate permissions available for successful login to the server or simply the login details entered are not correct. No matter which SQL Server edition is in use, this error will be thrown by the application if there is complete login details are not provided.

How To Fix SQL Server Error
How To Fix SQL Server Error


When error messages are received on screen, a description is shared along with that gives an idea of what actually the problem is. But for users encountering SQL Error 18456, the bad news is this code comes up with no reason for the login failure. Basically, this is done in order to protect unauthorized entrance to the server (particularly, for scenarios where someone is trying to login using guess info). Nevertheless, the administrator of the server can check out reason for the problem through event log.

Possible Causes: 

1)   The server login details are not correct, i.e. either the username or the password is wrong.

2)   When SQL server is logged in for the first time, error 18456 can be encountered. This happens when “Windows Authentication” is activated under the security section and for that reason the SQL server is not able to acknowledge the user.

3) Another reason for the error could be an expired login password. This sometimes happens when attempt to disable the username on server is made

Fix It: 

1)   The very first step in troubleshooting is to ascertain that the login credentials for the server are correct.

2)   Use SQL System Administrator credentials if Windows authentication is enabled but still the error is received on screen. In addition to this, make sure that the Windows Active Directory comprises of information related to SQL login. If in case, a user has to be added to the SQL database, then Server Admin Access and Password must be available.


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3)  If SQL Server authentication mode is enabled, it is important that System Admin credentials are available. But before login, ascertain that the password is not expired. To check this out, open SSMS, navigate to Server name and then choose “Properties”.

How To Fix SQL Server Error 18456
How To Fix SQL Server Error 18456

To check out if the option for password expiration is activated, go to “General” tab and verify if the “Enforce Password Expiration” is enabled/disabled.

How To Fix SQL Server Error 18456
How To Fix SQL Server Error 18456

4) To check the status of account, click on “Status” tab. The option “Login is Locked Out” will not be enabled if the account is unlocked.

How To Fix SQL Server Error 18456
How To Fix SQL Server Error 18456

5) Check out which security mode is exactly used by SQL server: Windows or Mixed. To verify, select the database to be checked, right click on it, and then select “Properties”. Click on the Security tab and verify the server authentication.

How To Fix SQL Server Error 18456
How To Fix SQL Server Error 18456

If in case the Server authentication mode is changed, it is mandatory to restart the SQL Server instance so that the changes made are effective. The above mentioned work around to fix error 18456 can be a sure shot help. However, it is recommended to first go for minor fixes like login credentials, login mode etc. and then go for further fixes.  

Author: As author of MS Outlook Tools, Peter has experience more than 20 years in IT industry and he is now working with an expert data recovery firm. He has quality expertise in the Office products especially in Microsoft Outlook and love to solve users query by providing excellent solutions.

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