25 March,2013 by Jack Vamvas
The SQL Login Failed Error 18456 error was reported by an application owner
Error: 18456, Severity: 14, State: 5.
How to resolve the 18456 login failed message:
1) Identify the state. It was state 5 meaning : Invalid User ID
2) The most common reasons are wrong user name or misspelling the user name.
3) Is the application attempting to login using SQL Server authentication rather than Windows Authentication?
4) Is the application mistakenly attempting to logon using the database user name rather than the login name? Depending on how the DBA set mappings, it is possible the connection string was set up with the database user name rather than login name/
5) Use these queries to identify whether a valid logon exists and database users
select * from sys.server_principals select * from sys.database_principals