Badimageformatexception When Loading 32 Bit Dll, Target Is X86

System.BadImageFormatException when compiled using any cpu

After examining the dll's header it turns out that Nuget is the one performing the magic. If I set the target to x86/x64 nuget will include the according version of the dll during compile.

But if I target "Any CPU" nuget will pick the x86 version of the dll. Thus if I try to launch my application in 64 bit mode it will throw BIFE.

Could not load file or assembly ... An attempt was made to load a program with an incorrect format (System.BadImageFormatException)

I am pretty sure you're having a 32-bit / 64-bit conflict. It sounds like your main project might be set to 32-bit while the class its referencing is set to 64-bit. Try looking at this SO question and this one too. Between the two of them, you should be able to figure out your problem.

Troubleshooting BadImageFormatException

Verified build settings such as Platform Target are all the same (x86).

That's not what the crash log says:

Assembly manager loaded from: C:\Windows\Microsoft.NET\Framework64

Note the 64 in the name, that's the home of the 64-bit version of the framework. Set the Target platform setting on your EXE project, not your class library project. The XxxDevicesService EXE project determines the bitness of the process.

BadImageFormatException occurring when loading a native DLL in .NET 4.0

If you get a BadImageFormatException when interfacing with a native DLL, it almost always means that you are trying to interface with a 32-bit DLL while running in the 64-bit CLR, or vice versa.

When you run the sample applications, do the processes have *32 in the "Image Name" column of Task Manager's "Processes" tab? That indicates the applications are running in the 32-bit CLR. Check your own application as well. It is possible that the machine you are testing on only has a 32-bit .NET 2.0 runtime, but both 32-bit and 64-bit .NET 4.0 runtimes, or the other way around.

If you are distributing a native DLL with your .NET application, then you should set your startup project to target x86 or x64 (as opposed to AnyCPU), depending on whether the native libraries are 32-bit or 64-bit. You can always ship both 32-bit and 64-bit versions, and let the installer choose which binaries to install based on the client architecture.

Alternatively, you can ship both 32-bit and 64-bit DLLs with different file names, define separate P/Invoke stubs for each version, and decide which one to call at runtime. The easiest way to do this would probably be to wrap your native calls in an interface (e.g., INativeMethods) and choose which implementation to instantiate at runtime based on IntPtr.Size. With this method, you could still target AnyCPU.

BadImageFormatException. This will occur when running in 64 bit mode with the 32 bit Oracle client components installed

One solution is to install both x86 (32-bit) and x64 Oracle Clients on your machine, then it does not matter on which architecture your application is running.

Here an instruction to install x86 and x64 Oracle client on one machine:

Assumptions: Oracle Home is called OraClient11g_home1, Client Version is 11gR2

  • Optionally remove any installed Oracle client (see How to uninstall / completely remove Oracle 11g (client)? if you face problems)

  • Download and install Oracle x86 Client, for example into C:\Oracle\11.2\Client_x86

  • Download and install Oracle x64 Client into different folder, for example to C:\Oracle\11.2\Client_x64

  • Open command line tool, go to folder %WINDIR%\System32 (typically C:\Windows\System32) and create a symbolic link ora112 to folder C:\Oracle\11.2\Client_x64 (see commands section below)

  • Change to folder %WINDIR%\SysWOW64 (typically C:\Windows\SysWOW64) and create a symbolic link ora112 to folder C:\Oracle\11.2\Client_x86, (see below)

  • Modify the PATH environment variable, replace all entries like C:\Oracle\11.2\Client_x86 and C:\Oracle\11.2\Client_x64 by C:\Windows\System32\ora112, respective their \bin subfolder. Note: C:\Windows\SysWOW64\ora112 must not be in PATH environment.

  • If needed set your ORACLE_HOME environment variable to C:\Windows\System32\ora112

  • Open your Registry Editor. Set Registry value HKLM\Software\ORACLE\KEY_OraClient11g_home1\ORACLE_HOME to C:\Windows\System32\ora112

  • Set Registry value HKLM\Software\Wow6432Node\ORACLE\KEY_OraClient11g_home1\ORACLE_HOME to C:\Windows\System32\ora112 (not C:\Windows\SysWOW64\ora112)

  • You are done! Now you can use x86 and x64 Oracle client seamless together, i.e. an x86 application will load the x86 libraries, an x64 application loads the x64 libraries without any further modification on your system.

  • Probably it is a wise option to set your TNS_ADMIN environment variable (resp. TNS_ADMIN entries in Registry) to a common location, for example TNS_ADMIN=C:\Oracle\Common\network.

Commands to create symbolic links:

cd C:\Windows\System32
mklink /d ora112 C:\Oracle\11.2\Client_x64
cd C:\Windows\SysWOW64
mklink /d ora112 C:\Oracle\11.2\Client_x86

Notes:

Both symbolic links must have the same name, e.g. ora112.

Despite of their names folder C:\Windows\System32 contains the x64 libraries, whereas C:\Windows\SysWOW64 contains the x86 (32-bit) libraries. Don't get confused.

BadImageFormatException Could not load file or assembly or one of its dependencies. An attempt was made to load a program with an incorrect format

As mentioned already it is due to wrong architecture either
a) Using x64 assembly with Windows x86
b) Using x86 assembly with x64 process or viceversa

For best results, ensure all .NET assemblies are built with "Any CPU", and same .NET profile (ie all using .NET Core, or Client Profile or Full .NET).

...or one dependency not being found at all, Enable Fusion Log to tell where is looking to gather the assemblies:

See How to enable assembly bind failure logging (Fusion) in .NET
and
http://www.hanselman.com/blog/BackToBasicsUsingFusionLogViewerToDebugObscureLoaderErrors.aspx

UPDATE: Given the error code 0x8007000b I am pretty sure is an architecture mismatch:
a) The dll may be Full .NET code, but not compiled with AnyCPU
b) The dll may be native code, and then you need a matching architecture (plus some calling its code using PInvoke)
c) The dll may be C++ CLI (mix of native/.NET code, again with wrong architecture).
d) The dll may be corrupt.

You may need to contact the 3rd party provider for support.
Also, this link mentions it could be a mismatch of .NET version.

Anyway, looks like the problem is narrowed.

Also if the DLL is partly native, it may need the MSVC runtime (as this question's answers mentions, Using 32-bit dll on 64-bit system shows 0x8007000B Error)

In that case the problem would be a dependency of dcasdk not being found.
You can check which Dependency Walker, see http://www.dependencywalker.com/
(it also has a profile mode where you profile an exe, and see the call to open a dll which failed at runtime).

WCF service library : BadImageFormatException with 32 bit dll

Thank you guys,

problem was with winscard.dll it uses Handles which are Int32
.all I changed is replacing the Int32 with Int64.

BadImageFormatException: Attempting to use a C++ DLL file in C#?

In x86 (in contrast to x64), there are different calling conventions. The language C (and extern "C" in C++) defaults to the cdecl calling convention, whereas C# defaults to the stdcall calling convention. Therefore, you must set the calling convention to cdecl in C#, like this:

[DllImport("MySimpleLib.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
public static extern int AddNumber(int a, int b);


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