Error: 18452 Login failed for user ‘null‘, …
• “Null” or ‘’ means that client windows token is not trusted
• Kerberos authentication is not available, fallback to NTLM (not in a domain, SPN not registered)
• Solution: Create the same account, password on the SQL Server
• Delegation may be required (at least one hop exists)
• Solution: use SQL Authentication or enable delegation
• SQL Server service account cannot query domain
Error: 18456 Login failed for user ‘name‘
• ‘Name’ means that principal is recognized, but not authorized to connect
• “Login Failed for user 'NT Authority\ANONYMOUS' LOGON“
• Reason: client is running under LocalSystem connects using NTLM
• Solution: Create a dedicated account on both machines
• “Login failed for user '<domain>\<machinename>$' “
• Reason: client is LocalSystem or NetworkService
• Solution: create login in SQL Server for client machine
• “Login failed for user ‘machinename\User’“
• Reason: client is local user and has no access
• Solution: create login in SQL Server for ‘machinename\User’
• “Login failed for user ‘user’“ (no “\”)
• Reason: SQL Login cannot connect
• Solution: Enable mixed mode
• Note that ‘user’ can be ‘null’ if client windows machine is not trusted, i.e. even SQL authentication requires cross-NTbox windows authentication
• SQL authentication can often be used as universal or the last resort solution to all these problems
Error: 18456, Severity: 14, State: XX.
• Client is recognized, but not authenticated
• State: XX is not reported back to the client
• Written into ERRORLOG
|
State |
Reason |
|
1 |
Generic error |
|
2 |
Login for remote login doesn’t exist in the server |
|
3,4 |
Failed to decrypt encrypted in-memory password |
|
5 |
SQL login doesn’t exist in the server |
|
6 |
Connecting SQL login has mismatched login type catalog |
|
7 |
Login disabled |
|
8 |
Password does not match |
|
9 |
Password is invalid (when changing password at logon) |
|
10 |
Account policy validation failed |
|
11 |
Windows login is not authorized to connect |
|
12 |
Sql login is not authorized to connect |
|
13 |
Server has paused, no logins are allowed |
|
14 |
Login cannot be used with this type of connection interface |
|
15 |
Database specified in the connection string is invalid |
|
16 |
Default database is invalid |
|
17 |
Default language is invalid |
|
18 |
Password cannot be changed for this type of login |
|
19 |
Failed to decrypt encrypted in-memory new password |
see also blogs.msdn.com/sql_protocols/archive/2006/12/02/understanding-kerberos-and-ntlm-authentication-in-sql-server-connections.aspx
