About SQL Server Error 18456 And Its Solution

When trying to connect to Microsoft SQL Server encounters you with an error 18456 that probably points towards authentication issue. This could be because you don't have enough rights or the credentials used are not correct. Therefore, this piece of segment shares information about SQL Server Error 18456 along with the consequences of it and the possible fixes that can be applied to it.

Understanding SQL Server Login Failed Error 18456

The failure encountered during a login performed on SQL Server, at most times, means that the server successfully received the connection request mentioned by you however; it isn't able to give you the access. This condition is caused by a number of possible reasons. Technically any error is converted to a state 1 error unless the server logging is checked, thus, the same happens with the discussed eventID too. Unfortunately, Microsoft doesn't offer error messages that could be useful. Therefore, below given are some of the possible explanations on the whys and wherefores of the SQL Server error code 18456.

On the failure of login performed on the server, the client shows up the following error message:

Fix SQL Server Error 18456

The message is structured in an undescriptive manner. This is done to prevent any kind of information from being disclosed to the potentially unauthenticated clients logging in to the SQL Server. Therefore, the state will always be shown as 1 despite the actual cause and type of the problem remaining mostly unknown. Nevertheless, the true reason behind the SQL Server error 18456 can be determined by the administrator with a look into the SQL Server's error log entry. A corresponding entry for the occurrence will certainly be written in it. For instance;

SQL Server Login Failed Error 18456

State of the error reflected here in the error log, depicts the actual cause behind the occurrence of MS SQL Server error code 18456. Source of the error and its nature can be determined with the state in which it is categorized. Information regarding such error states has been provided below:

  • 2 & 5: When the userID is invalid
  • 6: When an attempt is made to use Windows login with SQL Authentication
  • 7: Password is a mismatch and the login has been disabled
  • 8: Mismatching password
  • 9: Invalid password
  • 11 & 12: Failure of server access despite valid login attempt
  • 13: Service of the server is paused
  • 18: Password change needed

A possible cause to this condition could be any ranging from disabled userID on the server or password expiration probably caused the issue.

Fix SQL Server Error 18456

The administrator or anyone handling SQL Server error 18456 is suggested to take measures against this issue to resolve it and regain the access to server. Following are some of the suggested methods to be applied as a method:

  • If the connection is being established through SQL Server authentication method, then it is necessary to verify whether the server has been configured in a mixed authentication mode or not.
  • If the connection is being made via SQL Server Authentication, make sure that the server login exists and it is being correctly typed out.
  • With connection made via Windows Authentication, it is advised that the user ensure a proper login made to the correct domain.
  • Other than the above stated measures, you are requested to contact the SQL Server administrator when an error reflects state 1.


Repeatedly trying to log into the Server with the SQL Server Error 18456 being reflected as an output of no authentication or misspelled credentials could lead to permanent block out from the account. So it is better to use SQL password recovery tool to remove password from SQL Server Database.

SQL Server Recovery Manager