SQL (Structured Query Language) is basically a specific domain language, which is used in programming. It is designed for the process of Data Management in the RDBMS (Relational Database Management System) in addition to this, it can also be used in the RDBMS for stream processing. SQL is a popularly used language, however, sometimes it also faces some unwanted, unanticipated error messages. In this article, we will talk about ways to resolve one such error of SQL which is error code 18456. We will understand solutions to fix this error after taking an insight into basics of SQL.

Usually, an error code appears with a description that gives a clue about what is not right. However, in the case of the SQL server authentication error, not a single reason for failed login is shown. This is a planned policy in order to safeguard the server from unauthorised users like in a situation where a person is trying to access the server on the basis of guesswork. But the event log can always be checked by the administrator to figure out complete details about the appearance of SQL server error. The image below shows the Error 18456 Dialogue Box:-

The Appearance of MS SQL Server, Error: 18456 shows that invalid credentials have been entered while logging into the SQL Server. This 18456 error in SQL is encountered when the user’s request for connection was successfully received by its server name but the server failed to provide access to the user for a lot of reasons. These reasons are explained in the following section.

Potential Causes of SQL Server Login Failed Error 18456

1. Due to incorrect username or password, this error will be generated at the time of server login.

2. Users face error 18456 when an SQL Server instance is logged in for the very first time. It occurs when under security section, Windows authentication is enabled and SQL server fails to recognise the user.

3. Another possibility that causes the login failed error is when the password for login expires. It occurs even while disabling username on the server.

Methods to Fix SQL Server Error 18456

Manual Procedure to Fix Login Failed 18456 Server Error:

Method #1

With Windows Authentication, Login to MS SQL Server Management Studio.

Right click on the server and choose Properties in SQL Server Management Studio Object Explore.

After this, choose a page of security under the Server Properties.

Choose ‘SQL Server and Windows Authentication mode’ in Server Authentication and click on OK button.

Try Logging in with SA details after restarting MS SQL services.

Method #2

Assure that user enters correct login credentials including username and password and Run SQL Server through Run as Admin option in Windows Vista or Windows 7.

Use SQL SA credentials if Windows authentication is enabled then, check if Windows Active Directory has SQL login information linked to it or not. For adding user to SQL Server database, these must be available,

1. Server Administrator Access
2. System Admin (SA) Password

If to log in to the server, SQL server authentication mode is used then, SQL System Admin credentials are required. Assure that password is not expired before login. To check-
Open SSMS > Right-click Server name > Properties

Check if password expiration is enabled as-
Go to General Tab and see if Enforce Password Expiration is enabled or disabled.

Choose Status tab and see if the account is locked. If not, ‘Login is locked out’ will get disabled.
See if Windows/Mixed authentication is enabled or not. To check-
Go to database > Right-click > select Properties
Now, see the server authentication section in the security tab.
Restart SQL server to let changes occur if authentication mode is altered.

Alternate Procedure to Fix 18456 Login Error:

By using a third party SQL Password Recovery Tool, both unknown, as well as empty passwords of any length from SQL file, are reset. This tool lets users reset multiple passwords. The SQL Password Recovery software needs installation of SQL server on the system. Moreover, the tool performs the recovery of SQL server which was diseased by 18456 SQL error in a very less time. It has a very user-friendly interface and has a smooth processing on SQL database. Unlike the two solutions mentioned above, this method is highly reliable and easy to use. So, when 18456 SQL error strikes, the user has an easy and reliable approach to follow using this tool that is free from tedious manual methods.

Final Words

Though any of the above-mentioned methods can resolve MS SQL login failed error18456 yet it is advised to proceed in an orderly manner. However, if none of the above methods resolves 18456 error code then, go for the trusted third-party Recover SQL SA Password tool to reset missed SA password details in a short interval of time.