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loadFromContext MDA

The loadFromContext managed debugging assistant (MDA) is activated if an assembly is loaded into the LoadFrom context. This situation can occur as a result of calling Assembly.LoadFrom or other similar methods.

The use of some loader methods can result in assemblies being loaded in the LoadFrom context. The use of this context can result in unexpected behavior for serialization, casting, and dependency resolution. In general, it is recommended that assemblies be loaded into the Load context to avoid these problems. It is difficult to determine which context an assembly has been loaded into without this MDA.

Generally, an assembly was loaded into the LoadFrom context if it was loaded from a path outside the Load context, such as the global assembly cache or the AppDomainSetup.ApplicationBase property.

Configure applications such that LoadFrom calls are no longer needed. You can use the following techniques for doing so:

  • Install assemblies in the global assembly cache.

  • Place assemblies in the ApplicationBase directory for the AppDomain. In the case of the default domain, the ApplicationBase directory is the one that contains the executable file that started the process. This might also require creating a new AppDomain if it is not convenient to move the assembly.

  • Add a probing path to your application configuration (.config) file or to secondary application domains if dependent assemblies are in child directories relative to the executable.

In each case, the code can be changed to use the Assembly.Load method.

The MDA does not have any effect on the CLR. It reports the context that was used as a result of a load request.

The MDA reports that the assembly was loaded into the LoadFrom context. It specifies the simple name of the assembly and the path. It also suggests mitigations to avoid using the LoadFrom context.

<mdaConfig>
  <assistants>
    <loadFromContext />
  </assistants>
</mdaConfig>

The following code example demonstrates a situation that can activate this MDA:

using System.Reflection;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            // The following call caused the LoadFrom context to be used
            // because the assembly is loaded using LoadFrom and the path is 
            // located outside of the Load context probing path. 
            Assembly.LoadFrom(@"C:\Text\Test.dll");
        }
    }
}
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