Cannot Use Shares with LMCompatibilityLevel set to Only NTLM 2 Authentication

ID: Q236414

The information in this article applies to:

Microsoft Windows NT Server versions 4.0 SP4, 4.0 SP5
Microsoft Windows NT Workstation versions 4.0 SP4, 4.0 SP5

SYMPTOMS

After you change the type of authentication to use only NTLM version 2, shares may not be accessible on other computers.

CAUSE

Starting in Windows NT 4.0 Service Pack 4 (SP4), Microsoft provided an enhancement to control the type of security used for authentication using NTLMSSP. A new registry key named LMCompatibilityLevel was added. With the key set to Allow only NTLMv2, the local RDR does not succeed in getting credentials.

RESOLUTION

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:

http://www.microsoft.com/windows/servicepacks/

Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem was first corrected in Windows NT 4.0 Service Pack 6.

MORE INFORMATION

For additional information about LMCompatibility settings, please click the article number below to view the article in the Microsoft Knowledge Base:

Q147706 How to Disable LM Authentication on Windows NT

Because of the increased security level, the NET USE command may not work when the domain is defaulted. This is because the defaulted or non-existent domain is rejected at this security level. For this command to work the domain name must be supplied.

Additional query words:

Keywords : kbbug4.00 kbfix4.00 NT4SP6Fix
Version : winnt:4.0 SP4,4.0 SP5
Platform : winnt
Issue type : kbbug