C# – MetadataException: Unable to load the specified metadata resource

ado.netcentity-frameworknet

All of a sudden I keep getting a MetadataException on instantiating my generated ObjectContext class. The connection string in App.Config looks correct – hasn't changed since last it worked – and I've tried regenerating a new model (edmx-file) from the underlying database with no change.

Anyone have any ideas?

Further details: I haven't changed any properties, I haven't changed the name of any output assemblies, I haven't tried to embed the EDMX in the assembly. I've merely waited 10 hours from leaving work until I got back. And then it wasn't working anymore.

I've tried recreating the EDMX. I've tried recreating the project. I've even tried recreating the database, from scratch. No luck, whatsoever.

Best Answer

This means that the application is unable to load the EDMX. There are several things which can cause this.

You might have changed the MetadataArtifactProcessing property of the model to Copy to Output Directory.
The connection string could be wrong. I know you say you haven't changed it, but if you have changed other things (say, the name of an assembly), it could still be wrong.
You might be using a post-compile task to embed the EDMX in the assembly, which is no longer working for some reason.

In short, there is not really enough detail in your question to give an accurate answer, but hopefully these ideas should get you on the right track.

Update: I've written a blog post with more complete steps for troubleshooting.

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C# – Error message ‘Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.’

This error has no true magic bullet answer. The key is to have all the information to understand the problem. Most likely a dynamically loaded assembly is missing a referenced assembly. That assembly needs to be in the bin directory of your application.

Use this code to determine what is missing.

using System.IO;
using System.Reflection;
using System.Text;

try
{
    //The code that causes the error goes here.
}
catch (ReflectionTypeLoadException ex)
{
    StringBuilder sb = new StringBuilder();
    foreach (Exception exSub in ex.LoaderExceptions)
    {
        sb.AppendLine(exSub.Message);
        FileNotFoundException exFileNotFound = exSub as FileNotFoundException;
        if (exFileNotFound != null)
        {                
            if(!string.IsNullOrEmpty(exFileNotFound.FusionLog))
            {
                sb.AppendLine("Fusion Log:");
                sb.AppendLine(exFileNotFound.FusionLog);
            }
        }
        sb.AppendLine();
    }
    string errorMessage = sb.ToString();
    //Display or log the error based on your application.
}

C# – How to remedy “The breakpoint will not currently be hit. No symbols have been loaded for this document.” warning

Start debugging, as soon as you've arrived at a breakpoint or used Debug > Break All, use Debug > Windows > Modules. You'll see a list of all the assemblies that are loaded into the process. Locate the one you want to get debug info for. Right-click it and select Symbol Load Information. You'll get a dialog that lists all the directories where it looked for the .pdb file for the assembly. Verify that list against the actual .pdb location. Make sure it doesn't find an old one.

In normal projects, the assembly and its .pdb file should always have been copied by the IDE into the same folder as your .exe, i.e. the bin\Debug folder of your project. Make sure you remove one from the GAC if you've been playing with it.

Best Answer

Related Solutions

C# – Error message ‘Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.’

C# – How to remedy “The breakpoint will not currently be hit. No symbols have been loaded for this document.” warning

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