PRB: ODBC Error Message 1526 - "Connectivity Error" (239714)

SYMPTOMS

When attempting to connect to an external data source using SQLCONNECT(), the following errors appear:

Connectivity error: [Microsoft][ODBC Driver Manager] Function sequence error

- or -

The ODBC resource DLL (Drive:\Path\odbcinit.dll) is a different version than the ODBC driver manager (Drive:\Application_Path\odbc32.dll)

You need to reinstall the ODBC components to ensure proper operation"

This is followed by another error message:

"Initialization of the dynamic link library Drive:\Application_Path\odbc32.dll failed. The process is terminating abnormally."

At other times, the same SQLCONNECT() command may work with no problem.

CAUSE

This behavior occurs when ODBC support files, incompatible with ODBC support files in the Windows System directory, are copied to the application directory and then loaded into memory.

Files copied to the application directory of the distribution tree and included in setup diskettes created with the setup wizard are copied to the application directory during installation of the application.

RESOLUTION

Shut down Visual FoxPro. Remove the ODBC32.DLL, ODBC32INT.DLL, and any other ODBC components from that current application directory that are not compatible with the ODBC components in the Windows system directory. Restart Visual FoxPro.

ODBC Components should be distributed by checking the ODBC drivers check box in step 2 of setup wizard.

MORE INFORMATION

SQLCONNECT() loads the relevant ODBC components into memory, if they are not already loaded. Visual FoxPro searches for the ODBC components in the current directory before loading components from the Windows System directory. Any ODBC components that are not found in the current directory are loaded from the Windows system directory. Keeping ODBC components in the application directory increases the likelihood of a version mismatch and/or incompatibility with components located in the Windows System folder.

Steps to Reproduce the Behavior

From the Start button, select Settings, select Control Panel and then open the ODBC Administration applet. Create a new DSN to any data source.
Launch Visual FoxPro and set the default directory to a clean directory that does not contain any files.
Type ? SQLCONNECT() in the Command window and select the DSN created in step 1 from the dialog box.
Shut down and restart Visual FoxPro to unload the ODBC files in memory.
Launch Windows Explorer and copy a version of ODBC32.DLL, earlier than the version of ODBCINT.DLL located in the Windows System directory, to the directory that was set as the default directory in step 3.
Launch Visual FoxPro and set the default directory to the directory that now contains an outdated copy of ODBC32.DLL.
Type ?SQLCONNECT() in the Command window and select the DSN created in step 1 from the dialog box. Note that one of the error messages listed in the SYMPTOMS section of this article appears.