Error 18456, Severity 14: Login Failed States
Login Failed states summary
State	Description
1	Only state returned in SQL 2000. Server is in Single-User Mode (2005).
2 and 5	Invalid User Id
6	Attempt to use a windows login name with SQL Authentication
7	Login disabled and password mismatch
8	Password mismatch
9	Invalid Password
10	Read Ref Link #2
11 and 12	Valid login but server access failure; Default Database access failure. Or Initial database connection failure in connection string.
13	SQL Server service paused
16	User doesn’t have permission to target database
18	Change password required
23	Server in process of shutting down, and user attempted to login.
27	Initial database could not be determined for session
38	Initial database could not be determined for session (SQL 2008)
40	Default database could not be accessed (SQL 2008)