Microsoft OLE DB Provider for ODBC Drivers error ’80004005′
[Microsoft][ODBC Driver Manager] The specified DSN contains an architecture mismatch between the Driver and Application
/path/to/dsn.asp, line 6

Well that’s interesting.  It’s mostly interesting because of what was actually on line 6 of this file:

Conn.Open “dsn=dsnName;uid=user;pwd=pass;”

Googling kept pointing me to it being a 32bit application running in 64bit mode.  All the resolutions were mostly explaining that the application needs to be recompiled, yadda, yadda.  Obviously this .asp file isn’t a “32bit file”, and well what am I supposed to tell my customers, that they need to only use 64bit .mdb files?

The solution was actually simple and had been something I’d read a few days before at iis.net about 32bit mode worker processes.

To configure 32-bit mode for the server

• Open a command prompt and run the following:

%windir%\system32\inetsrv\appcmd set config -section:applicationPools -applicationPoolDefaults.enable32BitAppOnWin64:true

Or you can just toggle this option in the Advanced Settings for the Application Pool for which the site is running. Either way works just fine.

I suppose on a shared web server for which I have no daily knowledge or control over what my customers are doing, it would be a best practice to turn 32bit mode for all sites by default and if an opportunity or need arises to switch back to native 64bit mode, then all the better.

I would have expected there to be no problems with most of them. I started out with a dinky little site that uses a small Microsoft Access Database.  This site uses a standard DSN to access the .mdb. I proceed to go to the Administrative Tools and open the ODBC Data Source Administrator window and add a new DSN for the .mdb and lo and behold I see the following nearly empty window:

<– This of course is no good! Where are all the other data drivers? Apparently all the regular ones we are used to seeing in 32bit Windows no longer exist as 64bit drivers.  The trick is to execute %windir%\SysWOW64\odbcad32.exe.

<– This will give you the ability to add the rest of the 32bit Data Sources such as Microsoft Access (.mdb).