One potentially perplexing error that may be raised when using Oracle Data Provider for .NET (ODP.NET) is "The provider is not compatible with the version of Oracle client". The reason I say "potentially perplexing" is that the error can be raised in a situation that doesn't necessarily seem to agree with the wording of the message. More on that later.
ODP.NET consists of both managed and unmanaged components. The managed component is the Oracle.DataAccess.dll and one of the key unmanaged components is the OraOpsXX.dll which I refer to as the bridge dll. The exact name of OraOpsXX.dll depends on the ODP.NET version as well as the .NET Framework version. In this post I am using ODAC 11.1.0.6.21 which includes ODP.NET versions targeted to the .NET Framework 1.x and 2.x versions. Beginning with the 10.2 versions of ODP.NET the .NET Framework major version is pre-pended to the ODP.NET version to differentiate between 1.x and 2.x of the .NET Framework. Therefore, the Oracle.DataAccess.dll I am using will report 2.111.6.20 as its version number. The corresponding OraOpsXX.dll will be named OraOps11w.dll and is found in the %ORACLE_HOME%\bin directory if using a full install or (typically) in the root folder of an Instant Client install.
I'll show what I think are the three most common reasons for this error. In order to do so, I use a (very) simple C# console application:
using System;
using System.Data;
using Oracle.DataAccess.Types;
using Oracle.DataAccess.Client;
namespace NotCompatibleTest
{
class Program
{
static void Main(string[] args)
{
/*
* connection string using EZCONNECT format
* be sure to change for your environment
*/
string constr = "user id=hr;" +
"password=hr;" +
"data source=liverpool:1521/V112;" +
"enlist=false;" +
"pooling=false";
/*
* create and open connection
*/
OracleConnection con = new OracleConnection(constr);
con.Open();
/*
* write server version to console
*/
Console.WriteLine("Connected to Oracle version {0}",
con.ServerVersion);
/*
* explicit clean-up
*/
con.Dispose();
}
}
}
As you can see this simply connects to a database, writes the server version to the console window, and exits. However, it is sufficient to use ODP.NET and for the purposes here. I simply execute this sample in debug mode from within Visual Studio for each of the "tests".
Cause 1: OraOpsXX.dll is Wrong Version (and Hence the Client is Too)
This is a typical case and the message text makes the most sense for this case. Here, the correct version can not be found. How might this occur? One easy way is when you develop your application using 11.1.0.6 of Oracle Client and ODP.NET and then deploy to a machine that has a lower version of Oracle Client and ODP.NET installed. This is what the error looks like in debug mode with an unhandled TypeInitializationException when instantiating the OracleConnection object in the sample code:
Cause 2: OraOpsXX.dll is Missing
In order to simulate OraOpsXX.dll missing, I rename my OraOps11w.dll in %ORACLE_HOME%\bin to OraOps11wXX.dll and execute the sample. Sure enough, I get the same error as above. Here the message may not make as much sense. Instead of "The provider is not compatible with the version of Oracle client" it might be better if the message indicated the real issue is that OraOpsXX.dll can't be located.
Cause 3: The tricky one
This cause is certainly less intuitive than either Cause 1 or Cause 2. As mentioned earlier, OraOpsXX.dll is unmanaged code. It also has a dependency on the Microsoft C runtime, in particular version 7 of the C runtime which lives in msvcr71.dll and which many systems have on the system path. However, if that file is not on the system path or in the same directory as OraOpsXX.dll you will receive the "The provider is not compatible with the version of Oracle client" message!
If you are receiving "The provider is not compatible with the version of Oracle client" messages in your environment perhaps it is due to one of the three causes here.
