Question: I am currently developing on a Win7-32bits computer. Everything works fine. It's a ASP.NET application.

I was able to use Microsoft's Oracle deprecated .NET provider to connect to Oracle (using 32 bit instant client) and also ODP.NET. No problems at all. Application runs fine.

The problem comes when I deploy it to IIS7 on Windows 2008 Server 64bit computer. I can't get Microsoft's deprecated .NET provider or ODP.NET to work easily.

Is there a straightforward way to use a 32bit based ODP.NET or Microsoft's Oracle deprecated .NET provider in Windows 2008 Server 64bits?

DLL hell here!

Thanks.

Answer: 
Since this question is unanswered I'll add a link to another answer I created a while ago even though this question is very old.

[Is ODP.NET required for Oracle 11g Client?](https://stackoverflow.com/questions/1160218/is-odp-net-required-for-oracle-11g-client/13987366#13987366)

In general, change to `Oracle.ManagedDataAccess` (the managed code version of the ODP.NET client made by oracle) instead of the non-managed alternatives. This will help you a lot with "bittyness".
if you set IIS to run 32 Bits then I can confirm that the odp.net driver should work without problem as long as it's the 32 bit client. <http://support.microsoft.com/kb/894435>.

I've done this in iis for websites in the recent past and for our winforms app have set it to be x86 build so we always get the 32 bit odp providers on a 64 bit os (though you can do it with corflags as well).

Cheers,
Crocked