Microsoft SQL Server error code 18456 denotes a failed login attempt which may be due to an incorrect password entry. Generally, it happens even if the username is accepted. And the error message displayed does not define the reason. However, administrators can check the error details in the event log to get a clear picture of the problem.
This error may be interpreted as a mechanism to prevent unauthorized persons from accessing the server by guessing the credentials. But, genuine users may find it hard to overcome the problem.
Probable causes of SQL server login error code 18456
SQL Server login failures can happen due to various reasons.
Resolution to SQL error code 18456
When an SQL Server is started for the first time, there is a possibility that ‘Windows authentication’ is enabled under the security option. In such situation, the server will not recognize the user and user will get the failed login 18456 error. If you want to login through ‘SQL Server Authentication’, then enable it by following the steps:
But if you want to use the ‘Windows authentication’ option, then it will be better if an administrator provides admin rights to the user, so that he must be able to login without any hassle.
All the above mentioned methods are used to overcome login problems. However, they cannot help when SQL database is corrupt or mdf files are inaccessible. To recover SQL data and to repair the mdf files in such cases, you need an efficient mdf recovery tool like Kernel for SQL Database Recovery. It scans, analyzes, and repair mdf or ndf file and brings back all the precious data within no time.