Aug 7, 2012

0 Outlook fail connecting to Exchange Server

Outlook fail to connect

Windows 7 computers refuse to connect to Exchange server.

Otherwise user is able to use Outlook Web Application.

Problem is in  LmCombatibilityLevel registry key

By default it's supposed to have value :  0

Clients use LM and NTLM authentication, but they never use NTLMv2 session security.
Domain controllers accept LM, NTLM, and NTLMv2 authentication.

The key is highlighted above. I believe Exchange 2010 and Windows 2008 R2 domain use NTLMv2 by default. But how come the default settings is ZERO. The setting 1 makes lots of sense. And changing to 1 resolved my issue. Here is how you resolve the issue if you are facing the same issue.

  1. Open Registry Editor by running Regedit.exe.

  2. Browse to HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Control > Lsa

  3. Right click on the right side window, Click New > DWORD (32-bit) Value, type the name LmCompatibilityLevel  and press Enter.

  4. Double click on LmCompatibilityLevel key and add the value as 1.Click OK.

  5. Close Registry Editor and Reboot the computer.


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