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.