Could not load file or assembly for Oracle.DataAccess in .NET

Question

When I try to run a simple program to access oracle I am getting this message

Could not load file or assembly 'Oracle.DataAccess, Version=2.111.7.20, Culture=neutral, PublicKeyToken=89b483f429c47342' or one of its dependencies. The system cannot find the file specified.

I checked \windows\assembly and it's in there, but it's not in GAC (gacutil -l). I can't add into GAC (gacutil -i [path]. I get 'unknown error'.

Anyone has the same experiencing?

Answer 1

I'm going to give you the answers from what I've just went through on Windows Server 2008 R2 which is a 64 bit operating system. The application suite of libraries I was given were developed using .net 3.5 x86 with the older DLL libraries and I was stuck because I had installed the newer x64 clients from oracle.

What I found was the following: Install the latest x64 client from Oracle for Windows Server 2008. I believe this would be the 2.7.0 client. When you select the installation, make sure you do custom and select the .NET libraries. Configure your tnsnames files and test your tnsping against your data source.

Next, if you are running a 32 bit application, install the same version of the client for 32 bit. Also, follow the same installation routine, and select the same home.

When your finished, you will find that you have a single app/product with two client directories (Client1 and Client2).

If you navigate to the windows/assemblies directory you will find that you have a reference to the Oracle.DataAccess.dll (x2) with one for x86 and one for AMD64.

Now, depending on if you have developers or are developing on the machine yourself, you may be ok here, however, if they are using older drivers, then you need to perform one last step.

Navigate to the app\name\product\version\client_1\odp.net\publisher policy\2.x directory. Included in here are two policy files. use gacutil /i to install the Policy.2.111.Oracle.DataAccess.dll into the GAC. This will redirect legacy oracle ODP calls to the newer versions. So, if someone developed with the 10g client, it will now work with the 11 client.

FYI -- Some may be installing the latest ODP.NET with the 2.111.7.20. The main oracle client itself comes with 2.111.7.0 .. I've not had any success with the 7.20 but have no issues with the 7.0 client.

Answer 2

I was compiling in x64, just use x86 and it will solve the problem

Answer 3

The solution is quite simple, it is all a matter of how you define things on the server / workstation in relation to your visual studio project.

First check the version of the Oracle library that you are using, in your case 2.111.7.20. Next go to the Windows GAC located in your windows home->assembly folder.

Scroll down to the Oracle dll, it is normally called Oracle.DataAccess or Oracle.Web. Find the right version of it and note down if it says x86 or AMD64.

In visual studio ensure that your target platform is the same as the dll in the GAC, so if it says x86 in the GAC folder ensure that the target platform is x64 and other x64. You can set this in Visual Studio project properties, under build/platform target.

Also ensure that your reference, under references in your project points to this exact same version on your development computer.

With this everything should work fine.

What I normally do is to check the server first as it is often easier in an enterprise environment to change the version of your local dependencies, then to ask a server administrator to do an installation of a different dll.