A co-worker and I have been working on converting from SQL Server to Oracle 11g. Both of us have downloaded the 32-bit visual studio tools and installed them (http://www.oracle.com/technetwork/database/windows/downloads/index-101290.html). We've also downloaded and installed the ODAC 64-bit drivers (XCopy only - http://www.oracle.com/technetwork/database/windows/downloads/index-090165.html). Both of us can build/run the solution (which is sync'd using a repository) and communicate with Oracle (i.e. we are able to query an Oracle table and display the results). However, I get this warning message in Visual Studio that my co-worker does not get. I was hoping someone has seen it before and knows of a solution. The warning message is: ASP.NET runtime error: Could not load file or assembly 'Oracle.DataAccess' or one of its dependencies. An attempt was made to load a program with an incorrect format. We are running IIS7 in 64-bit mode. The message only appears for ASPX pages I have open. Also, we are using .NET4.0 framework on Windows 7 64-bit. The Oracle drivers seem to be in the GAC32 and GAC64 locations. Any ideas?
When you build your app, check to see if you are targeting "AnyCPU". If so try switching it to x64 or win32, whichever you are targeting. ODP.NET for the appropriate "bitness" must be installed for what you are targeting.