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Article ID: 954415 - Last Review: July 23, 2008 - Revision: 1.0
Error message when you try to log on to a domain controller from a Windows Server 2008-based computer or from a Windows Vista-based computer: "Logon failure: Unknown username or bad password"
Consider the following scenario:
- You try to log on to a domain controller from a Windows Server 2008-based computer or from a Windows Vista-based computer.
- The domain controller runs an operating system that is earlier than Windows Server 2008.
In this scenario, the logon is unsuccessful. Additionally, you receive the following error message:
Logon failure: Unknown username or bad password
This issue occurs if the following account options are turned on in the properties of the user account:
- Use DES encryption types for this account
- Do not
require Kerberos preauthentication
To work around this issue, turn off the account options. To do this, follow these steps:
- On the domain controller, click Start, point to Administrative Tools, and then click Active Directory Users and Computers.
- Expand your domain, and then click Users.
- In the details pane, right-click the user account name that you used to log on to the domain controller, and then click Properties.
- Click the Account tab, and then click to clear the following check boxes in the Account options list:
- Use Kerberos DES encryption types for this account
- Do not
require Kerberos preauthentication
- Click Apply, and then click OK.
- Exit the Active Directory Users and Computers snap-in.
- Verify that you can successfully log on to the domain controller.
APPLIES TO
- Windows Server 2008 Enterprise
- Windows Server 2008 Datacenter
- Windows Server 2008 Standard
- Windows Web Server 2008
- Windows Server 2008 for Itanium-Based Systems
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