MP Control Manager detected NLB MP is not responding to HTTP requests. The http status code and text is %1, %2.%12 Possible ...

%11MP Control Manager detected NLB MP is not responding to HTTP requests.  The http status code and text is %1, %2.%12

Possible cause: MP encountered an error when connecting to SQL Server. 
Solution: Verify that the SQL Server is properly configured to allow Management Point access.   Verify the account used by the MP to connect to the SQL Server is a member of the SMS_SiteSystemToSQLConnection_ group on the SQL Server, that the account is not locked out, and that the account password is not expired.  

Possible cause:  The SQL Server Service Principal Names (SPNs) are not registered correctly in Active Directory
Solution:  Ensure SQL Server SPNs are correctly registered.  Review Q829868.

Possible cause: Internet Information Services (IIS) isn't configured to listen on the ports over which the site is configured to communicate. 
Solution: Verify that the designated Web Site is configured to use the same ports which the site is configured to use.

Possible cause: The designated Web Site is disabled in IIS. 
Solution: Verify that the designated Web Site is enabled, and functioning properly.

Possible cause: The MP ISAPI Application Identity does not have the requisite logon privileges. 
Solution: Verify that the account that the MP ISAPI is configured to run under has not been denied batch logon rights through group policy.

For more information, refer to Microsoft Knowledge Base article 838891.
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