BUG: MDAC: SQL Server Driver May Return Error "Login Failed"

ID: Q216848

The information in this article applies to:

Microsoft ODBC Driver for SQL Server, version 3.7
Microsoft SQL Server versions 6.5, 7.0

BUG #: 54023 (SQLBUG_70)
BUG #: 18608 (SQLBUG_65)

SYMPTOMS

An ODBC application may fail to connect to SQL Server 6.x with the following error message returned:

[28000][Microsoft][ODBC SQL Server Driver][SQL Server] Login failed (4002)

This problem occurs when applications use the Microsoft Data Access Components (MDAC) 2.1 version of the SQL Server driver (3.70.623) to make trusted connections to SQL Server 6.x and an older version (version 6.x or earlier) of the SQL Server client-side Net-Library DLL is the first on the path.

If all client-side Net-Library DLLs are updated to the SQL Server 7.0 version, this problem does not occur. Applications will not experience this problem when connecting to SQL Server 7.0. Finally, if the ODBC application is started from a directory that contains the updated client-side Net-Library DLL, the problem does not occur either.

CAUSE

The MDAC 2.1 SQL Server driver is designed to automatically load the correct version of Net-Library from the <Winntroot>\System32 directory if an older version of Net-Library is initially loaded. However, when loading the Net-Library DLL from the System32 directory for the second time, the driver incorrectly assumes it is making a trusted connection to SQL Server 7.0, resulting an invalid login packet sent. This causes the connection to fail and the error to be returned.

WORKAROUND

This problem can easily be avoided by updating all Net-Library DLLs on the path, including those in the current directory where the application is started. MDAC 2.1 installs the following Net-Library DLLs to the System32 directory, all with the date of 11/13/98:


   DBNMPNTW.DLL
   DBMSRPCN.DLL
   DBMSSOCN.DLL
   DBMSSPXN.DLL
   DBMSVINN.DLL
   DBMSADSN.DLL
   DBMSSHRN.DLL

These are the correct versions of Net-Library DLLs and should be used with the MDAC 2.1 SQL Server driver. To ensure that there are no older versions of these DLLs somewhere on the path, it is suggested that you search the hard disk(s) for those DLLs and replace them with the new ones. For example, if the Named Pipes Net-Library is used for the ODBC application, you should search the hard disks for DBNMPNTW.DLL (especially the directory where the application executable file is located), and either rename the old DLLs or replace them with the new ones found in the System32 directory.

To verify whether MDAC 2.1 is installed on the system, start the ODBC Data Source Administrator from Control Panel, click the Drivers tab, and check the SQL Server driver version. If it is 3.70.623, then the MDAC 2.1 SQL Server driver is installed.

STATUS

Microsoft has confirmed this to be a problem in SQL Server version 6.5 and 7.0.

MORE INFORMATION

MDAC 2.1 is included with both SQL Server 6.5 Service Pack 5 and SQL Server 7.0. The problem is less likely to occur on a server running SQL Server 7.0 because the installation of SQL Server 7.0 will update the client-side Net-Library DLLs that it can find. On a SQL Server 6.5 computer, the Service Pack 5 upgrade does not update the client-side Net-Library DLLs to the SQL Server 7.0 version. Even if the MDAC 2.1 installation program copies the SQL Server 7.0 version of the Net-Library DLLs to the System32 directory, it does not update those DLLs in other directories (such as the Mssql\Binn directory). As a result, any ODBC applications that are started from those directories may encounter this problem when making trusted connections to SQL Server 6.x-based servers. For example, when SQL Server 6.5 is updated to Service Pack 5 and MDAC 2.1 is installed, replication distribution tasks may fail to connect to the distribution server with the same error in the history log.

Additional query words: integrated security named pipes socket tcp/ip sqlsrv32 sp sp5 sp5a netlib

Keywords : SSrvNet_Lib kbbug6.50 kbbug7.00
Version : WINDOWS:3.7; winnt:6.5,7.0
Platform : WINDOWS winnt
Issue type : kbbug