C#•11mo ago

❔ System.BadImageFormatException: Cannot load a reference assembly for execution.

Hello, I'm trying to debug this exception in my C# app. I've tried solutions from stack overflow - ie. cleaning and rebuilding the app; as well as updating the .NET framework that this app targets. But to no results. I'm at the point where each library needs to be checked if a library is causing this exception or if a library is completely missing. I'm curious if others here have experienced similar runtime exceptions in the past and if there are other considerations. Thank you for reading this post 🙂

13 Replies

333fred•11mo ago

You'll need to provide quite a bit more detail for anyone to help you with this

lexbit•11mo ago

Oh ok - fair. Wasn't sure if enough or too little.

lexbit•11mo ago

Here is the exception :

message.txt

333fred•11mo ago

You'll need to tell us what exactly you're doing, what assembly you're trying to load, how that assembly was created, etc. We're not mind readers, we can't just magically fix things without all the details 🙂

lexbit•11mo ago

To be honest, I'm not sure which assemblies are currently not being loaded. I've been trying other general solutions to potentially hone down on what the issue was. I'll be following up on that as I gather more info later on - it looks like atm I'll need to setup remote debugging (which is new to me)

Mashi•11mo ago

This is a runtime error? What happens if you restore all NuGet packages? If you're using Visual Studio, the NuGet manager usually tells you if there are any versioning issues. Though, I have found it to be finicky for large solutions.

Mashi•11mo ago

https://learn.microsoft.com/en-us/dotnet/api/system.badimageformatexception?view=netframework-4.0

BadImageFormatException Class (System)

The exception that is thrown when the file image of a dynamic link library (DLL) or an executable program is invalid.

Mashi•11mo ago

There's some code here for troubleshooting

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

public class Example
{
   public static void Main()
   {
      String[] args = Environment.GetCommandLineArgs();
      if (args.Length == 1) {
         Console.WriteLine("\nSyntax:   PlatformInfo <filename>\n");
         return;
      }
      Console.WriteLine();

      // Loop through files and display information about their platform.
      for (int ctr = 1; ctr < args.Length; ctr++) {
         string fn = args[ctr];
         if (! File.Exists(fn)) {
            Console.WriteLine("File: {0}", fn);
            Console.WriteLine("The file does not exist.\n");
         }
         else {
            try {
               AssemblyName an = AssemblyName.GetAssemblyName(fn);
               Console.WriteLine("Assembly: {0}", an.Name);
               if (an.ProcessorArchitecture == ProcessorArchitecture.MSIL)
                  Console.WriteLine("Architecture: AnyCPU");
               else
                  Console.WriteLine("Architecture: {0}", an.ProcessorArchitecture);

               Console.WriteLine();
            }
            catch (BadImageFormatException) {
               Console.WriteLine("File: {0}", fn);
               Console.WriteLine("Not a valid assembly.\n");
            }
         }
      }
   }
}

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

public class Example
{
   public static void Main()
   {
      String[] args = Environment.GetCommandLineArgs();
      if (args.Length == 1) {
         Console.WriteLine("\nSyntax:   PlatformInfo <filename>\n");
         return;
      }
      Console.WriteLine();

      // Loop through files and display information about their platform.
      for (int ctr = 1; ctr < args.Length; ctr++) {
         string fn = args[ctr];
         if (! File.Exists(fn)) {
            Console.WriteLine("File: {0}", fn);
            Console.WriteLine("The file does not exist.\n");
         }
         else {
            try {
               AssemblyName an = AssemblyName.GetAssemblyName(fn);
               Console.WriteLine("Assembly: {0}", an.Name);
               if (an.ProcessorArchitecture == ProcessorArchitecture.MSIL)
                  Console.WriteLine("Architecture: AnyCPU");
               else
                  Console.WriteLine("Architecture: {0}", an.ProcessorArchitecture);

               Console.WriteLine();
            }
            catch (BadImageFormatException) {
               Console.WriteLine("File: {0}", fn);
               Console.WriteLine("Not a valid assembly.\n");
            }
         }
      }
   }
}

lexbit•11mo ago

It doesn't return an error when I run dotnet restore in Visual Studio. - the version of windows I'm targeting is not the same as the one I'm building on (target Win10 LSTC - 1809 vs. Win10 22H2). I'm building against .Net 4.8 which is supported on 1809.

Mashi•11mo ago

I see, I didn't know there were versions of Window 10 that didn't support any version of .NET Framework 4. 🤔

333fred•11mo ago

There aren't

lexbit•11mo ago

That's the weird part. But - I have cut down the mystery today (at least getting closer). I've tried a remote debugging session to reproduce the error on the target machine and the exception did not show up. But the local installation has this error occur on runtime and it occurs when running a feature that involves either (System.Net.Http or System.Net.Json - I think; I could be totally wrong too...). I think it could be a possibility that the installer could be the cause of it and that a dll dependency is not being loaded or wasn't configured or just missing.

Accord•11mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ System.BadImageFormatException: Cannot load a reference assembly for execution.