Data source name not found and no default driver specified

[Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified

I had this error and want to let you know how it was resolved.

First, this was an ASP web application using a vb 6.0 dll to get data from a sql server 2005 database on a 64 bit windows server 2008 enterprise (vista like) server. I could only get the dll to work in component services as opposed to simply registering it.

It all worked fine upon setup, but after four windows updates one night, the error above was posted in the event viewer, and the web app crashed.

Here is the resolution:

In a 64 bit windows server operating system, there are TWO odbc managers. When you pull up the usual menu for the odbc / dsn system, it is for the 64 bit odbc manager, and 32 bit applications (vb 6.0) will not work using these dsn's.

This is where the 32 bit odbc manager is:

C:\Windows\SysWOW64\odbcad32.exe

I hope you do not have to go through what I and three Microsoft Support engineers had to to figure this out.

Jonathan