Oracle.DataAccess.Dll loading issue on x-64 machine

Solution 1:

The architecture (x86 or x64) of Oracle.DataAccess.dll must match the architecture of installed Oracle Client and both of them must match the architecture of your deployed application (i.e. whether you compiled at "AnyCPU" or "x86" or "x64").

"AnyCPU" will target to x64 on a 64-bit Windows.

The best solution is to install both x86 and x64 Oracle Client (and according ODP.NET) on your machine, then any combination will work. Here is an instruction how to do this: Install Oracle x86 and x64

An alternativ solution is to use the ODP.NET Managed Driver, this works in any case. You can download it from here: 64-bit Oracle Data Access Components (ODAC) Downloads