无法加载文件或程序集System.IO.FileNotFoundException

Question

The application i am developing is a simple remote chat application.

I am experiencing this exception when i try to run my application. I really do not understand when it talks about loading file or assembly.

"System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.IO.FileNotFoundException: Could not load file or assembly 'Client, Version=1.0.0.0"

try
{
   gt = (Greeting)Activator.GetObject(typeof(Greeting), "tcp://Localhost:7189/Greeting");
   handler = new MessageHandler(OnReceive);
   gt.Sender += handler;
}
catch(Exception ex)
{
   textBox2.Text = ex.ToString();
}

This exception is Thrown at this line

gt.Sender += handler;

Below is my Greetings class.

[Serializable]
public delegate void MessageHandler(string mymsg);
public class Greeting:MarshalByRefObject
{
    public event MessageHandler Sender;

    public override object InitializeLifetimeService()
    {
        return null;
    }

    public Greeting()
    {
    }

    public void postGreeting(string msg)
    {
        if (Sender != null)
        {
            Sender(msg);
        }
    }
}

Answer 1

I assume the handler is created within your Client assembly? A reference to the handler is passed to your server assembly when you subscribe to the Greetings.Sender event. As part of the deserialization on the server side it must resolve the handler type. As it lives within the Client assembly this must be accessible to the server assembly.

Build all of your assemblies into a single shared debug or release folder and try again.

Answer 2

使用Microsoft sysinternals进程监视器，配置该工具以监视应用程序的所有文件访问操作，然后您可以查看您的进程尝试访问的程序集。

Answer 3

the idea of using microsoft sysinternals process monitor worked perfectly for me. i was able to see that it was looking for one of the dependencies in the wrong folder.

Answer 4

If you experience Could not load file or assembly use the Assembly Binding Log Viewer (on disk called fuslogvw.exe and availbale from the .NET SDK) to find out exactly what your process is actually probing, either in the GAC or your application folder.

A typical logentry will hold info similar to this:

LOG: Processing DEVPATH.
LOG: DEVPATH is not set. Falling through to regular bind.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Post-policy reference: graphicfailtest.resources, Version=0.0.0.0, Culture=en-US, PublicKeyToken=null
LOG: Attempting download of new URL file:///C:/Program Files/Microsoft.NET/FrameworkSDK/Samples/Tutorials/resourcesandlocalization/graphic/cs/en-US/graphicfailtest.resources.DLL.

and you can then verify that it loads assemblies from a location you expect, inclusing if it is the correct version.

Probing from the msdn docs.