Orable DB and MVC 4 - Connection error (ORA-06413)

Question

I have a dll which is responsible for carrying out the consultations in the bank. Therein dll, in the connection class, I have a method that opens the connection to the bank and returns the connection to me, as shown below:

private OracleConnection _IniciarConexao()
{
    ///Limpa as variáveis de erro
    this.UltimaExcecao = null;
    this.Erros         = new List<Exception>();

    OracleConnection conexao = null;

    try
    {
        conexao = new OracleConnection("Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=***)(PORT=***)))(CONNECT_DATA=(SERVICE_NAME=****)(SERVER = DEDICATED))); User Id=***; Password=***;");

        conexao.Open();
    }
    catch (Exception ex)
    {
        this.UltimaExcecao = ex;
        this.Erros.Add(ex);
    }

    return conexao;
}

To dll used for Oracle references is the System.Data.OracleClient.dll Versão 2.0.50727.

That one dll is consumed by a web application using MVC 4 with C# and the .Net Framework 4.0.

When I use that dll on a project Windows Forms I can connect to the database without problems, but when I use in a system MVC or WebForms an error occurs in connection with the database.

The error that occurs is the ORA-06413. The image below can illustrate what happened:

I’m already on the second day of unsuccessful research on how to solve this problem.

When publishing the system to the production server it can connect normally, but in the local, to use debug mode, I cannot connect to the database.

Does anyone know how to fix this error, or any source that can tell me to fix this problem?

Answer 1

This error is commonly caused by incompatibility of architectures between the Oracle DLL and the application that is running. If you are using the 64bit version of the DLL for example, in Web projects, you must configure the IIS Application Pool to use 64bit or enable the IIS Express configuration in Visual Studio, if applicable:

• If you are using IIS, by default it runs as 64bit. If you need to force 32bit, Inside IIS Managed, expand "Application Pools", locate the Pool your application is using, right-click > Advanced Settings:

^{If the "Enable 32-Bit Applications" setting is True, the pool will run as 32bit, otherwise as 64bit.}

• If you are using IIS Express, inside Visual Studio, Go to TOOLS > Options > Projects And Solutions > Web Projects > and check the checkbox "Use the 64 bit version of IIS Express for web sites and Projects":

Answer 2

I think I found the problem.

I was testing a project that was a console application, using an Oracle database access dll identical to the one in the problem. The file . csproj was set as below:

<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
 <DebugSymbols>true</DebugSymbols>
 <DebugType>full</DebugType>
 <Optimize>false</Optimize>
 <OutputPath>bin\Debug\</OutputPath>
 <DefineConstants>TRACE;DEBUG</DefineConstants>
 <ErrorReport>prompt</ErrorReport>
 <WarningLevel>4</WarningLevel>
 <PlatformTarget>AnyCPU</PlatformTarget>
</PropertyGroup>

However, when I went to search the file . csproj of my console application, it was as below:

<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
 <DebugType>pdbonly</DebugType>
 <Optimize>true</Optimize>
 <OutputPath>bin\Release\</OutputPath>
 <DefineConstants>TRACE</DefineConstants>
 <ErrorReport>prompt</ErrorReport>
 <WarningLevel>4</WarningLevel>
 <Prefer32Bit>false</Prefer32Bit>
</PropertyGroup>

The solution was to copy this section of . csproj from dll, replacing the . csproj snippet from my console application with the dll snippet. After the replacement the problem was solved. I believe that VS2015 was getting lost when saving the dlls to be used, saving one part in bin/Release folder and another in bin/Debug folder.

Answer 3

The @Marcusvinicius response solved my problem for web projects, but I continued with a problem for desktop applications such as windows forms and console aplication.

Watching the @Hendrigwernner response I realized the tag <Prefer32Bit>false</Prefer32Bit>. I looked at the project properties and cleared this option in the project properties, in the tab build.

Making this modification the project worked correctly and the connection error did not appear anymore.

Answer 4

Adding the DLL directly can be a problem, especially considering that there may be a change of environments when publishing your application.

Instead of adding the DLL directly, use the official Nuget package of Oracle drivers:

PM> Install-Package Oracle.ManagedDataAccess