Fed Up With System.Data.Metadata.Edm.ObjectItemAssemblyLoader

16 Comments

• Posted a workaround in Connect. Please have a look.
  

• Hi Ken, did you ever figure out what was wrong? I am hitting the exact same error and I can't figure out what's wrong.
  

• @Joe: The workaround posted by Paresh says, "Do not use one EntityDataSource for two controls. Create two EntityDataSource controls for two different controls."
  
  I haven't been able to find where I'm doing that, so I still have the problem and it is really, really annoying on a live site.
  

• This issue is caused by the top call in your stack trace - Assembly.GetTypes(). This call enumerates all classes in the target assembly (the assembly with all your entity types in - usually created from an edmx file).
  One of your classes is inheriting, or using in it's static initialiser, a class that isn't referenced, or a newer or older version of a class that is referenced.
  
  Check all the references your entity project has in visual studio, it's very likely that one of them isn't copied to the bin folder correctly, or has a version mismatch.
  

• @Thomas:
  
  Thanks for your input. This problem has made for a very unstable ASP.NET 4 Web application. I can't count on the app to restart properly. I have to dirty the web.config file to make it compile and run again.
  
  What I don't understand about your analysis is why Assembly.GetTypes() sometimes works and sometimes doesn't. If the compiler is finding a version mismatch, why isn't there a tool to tell me where the problem is? Instead, I get a stupid error about MVC that I don't even use or reference.
  
  Still looking for a solution....
  
  Ken
  
  
  

• I'm getting the same error: "Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information". ASP.net 4.0, entity framework. The error occurs intermittently, and dirtying the web.config, seems to resolve the problem temporarily. I've tried making copies of share entity datasources so that each control references a distinct entity datasource control... I'll wait and see if this resolves it.
  

• A simple solution that works is:
  
  Add the following line to the webconfig
  
  ...
  
  
  
  ...
  
  
  
  Regards,
  
  www.dilowa.co.za
  

• the problem only occure when you bind the entitydatasource with some control in the design mode. it will not happen if you bind it in code behind.
  firstly, i never get this kind of error in my previous project, so after i got this kind of problem, i try to compare it to my old app.
  all the config and setting are the same. but i realize the problem occured after i install some additional feature for my telerik (i'm using telerik framework)
  after some research, finally i found that some reference have brought up the problem. after than i try to remove several unused reference such as wpf and silverlight.
  after i remove those reference my app work smoothly.
  hope this help
  

• Any news on this? I've tried rewriting the EntityDataSource in code behind, but it's a lot of work when you have a lot of datasources. And then, you've got to recompile if there are changes.
  

• @Cogsi
  
  Yes, I'm still getting it intermittently and annoyingly. I'm still wondering if it is somehow related to Telerik components. Anyone have a clue?
  
  Ken
  

• Thanks a lot!!!. This is the solution what i need.
  

• Great post - I've been at this for hours. Now I actually have a real error msg! Thanks again.
  

• Great I got the problem and solved it.
  just a small note the code needs small modification in order to compile on Vs2010
  
  For Each ex As System.Exception In reflerror.LoaderExceptions
  sb.AppendLine(ex.Message)
  Next
  

• I know this is old, but....
  
  I used this method to find out that my issue was coming from Microsoft.ReportViewer.DataVisualization. The ReportViewer references were set CopyLocal=true, and apparently that causes some issue (as found elsewhere on the net), they need to be in the GAC only (which they already were).
  
  In any event, thanks for the help, FWIW, here's the code in C#:
  
  System.Text.StringBuilder sb = new System.Text.StringBuilder();
  Exception objErr = Server.GetLastError().GetBaseException();
  Server.ClearError();
  
  if (objErr.GetType() == typeof(System.Reflection.ReflectionTypeLoadException))
  {
  System.Reflection.ReflectionTypeLoadException reflErr = (System.Reflection.ReflectionTypeLoadException)objErr;
  foreach (Exception ex in reflErr.LoaderExceptions)
  sb.AppendLine(ex.Message);
  }
  
  sb.AppendLine("
  Error Message: " + objErr.Message.ToString());
  sb.AppendLine("
  Stack Trace:
  " + objErr.StackTrace.ToString());
  Response.Write(sb.ToString());
  

• Your code had helped me, I was running out of my mind trying to get the purpose of that exception. After I had reinstalled VS 2010, I had to re-install a library that was referenced in my project (MVC 3, VS 2010). Now it works fine, I owe You a big beer. Thanks !
  

• Great code providen in the answer by Allen. One thing I would liked to known aswell was to know where to put this code therefore I would like to tell where I put it in the end. I added the following method
  
  protected void Application_Error(Object sender, EventArgs e)
  {}
  
  in the Global.asax.cs file. This will catch the error and is therefore a good place to put Allens code in. My problem was that Microsoft.Data.Odata couldn't be found