FileNotFoundException (DLL not found) - c#

I'm getting that strange error on one of client's machines. It throws FileNotFoundException, but that DLL is definitely right there in the folder with Executable.. Why it can't find it?
Please advise..

Psychic debugging, since you have not included the full exception details, is that you have a 32bit versus 64bit mismatch:
Your Executable is AnyCPU
The referenced DLL (or a downstream reference) is x86
The machine running the executable is 64bits
Basically, you'll have to recompile your C# executable with a Platform of x86 if you have any x86 DLL dependency (usually an unmanaged DLL).

The assembly may be missing one of its dependent assemblies.

Related

How to set platform architecture for csi.exe

I see the following error when running csi.exe:
System.BadImageFormatException: Could not load file or assembly
'xyz.dll' or one of its dependencies. is not a valid Win32
application. (Exception from HRESULT: 0x800700C1)
Compiling in Visual Studio raises a warning but compiles and runs without problems:
There was a mismatch between the processor architecture of the project
being built "MSIL" and the processor architecture of the reference
"xyz", "x86". This mismatch may cause runtime failures. Please
consider changing the targeted processor architecture of your project
through the Configuration Manager so as to align the processor
architectures between your project and references, or take a
dependency on references with a processor architecture that matches
the targeted processor architecture of your project.
So it seems I have to specify processor architecture when running csi.exe? How to do that?
Your assembly xyz.dll is compiled to only run in a 32bit process. This might be for a good reason (such as for example loading another native dll that is available with 32bit code only). In this case, use the solution presented below. It may also be for no good reason. In this case, change the target platform of xyz.dll.
The program CSI.exe (C# Interactive Compiler) is built in a way so that it will run as a 32bit executable on a 32bit version of Windows and it will run as a 64bit executable in a 64bit version of Windows.
When running as a 64bit executable, it will not be able to load an assembly that is built to only run in a 32bit process (such as your xyz.dll).
In order to change this, you can create a version of CSI.exe that runs as a 32bit process even on a 64bit version of Windows. Follow these steps:
Locate the file csi.exe, make a copy of it in the same directory and rename the copy to csi32.exe. You can find csi.exe in a path similar to "C:\Program Files (x86)\MSBuild\14.0\Bin\csi.exe"
Locate the file CorFlags.exe. You can find CorFlags.exe in a path similar to "C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.6.2 Tools\CorFlags.exe"
Open a commandline window as administrator.
Execute the following command using the correct paths for the two executable files
C:\Path\To\CorFlags.exe /32bit+ /force C:\Path\To\csi32.exe
You can now use csi32.exe in the place of csi.exe to run scripts that require assemblies/dlls which are only available in 32bit versions.

How do I reference a 32 bit DLL in a 64 bit project?

I've got a C# 2.0 project which is set to target 'Any Cpu', however it is referencing a C++ project that's building a 32 bit dll.
When I try to run my program on a 64bit machine I get the following error:
System.BadImageFormatException was
unhandled Message: Could not load file
or assembly TreeTMHook,
Version=1.0.2889.19619,
Culture=neutral, PublicKeyToken=null
or one of its dependencies. An attempt
was made to load a program with an
incorrect format.
How can I fix this?
Update
I want to be able to keep the main project as any cpu.
Thanks.
You'll need to build your .NET project as 32bit (x86 target) if you want it to correctly load a 32-bit DLL on a 64bit machine.
RE: Update:
If you want to keep your project as "Any CPU", you'll need a 32bit and a 64bit version of the DLL, and make sure the appropriate version is distributed with your app. If you can't build the other project as 64bit, you must build your .NET project as 32-bit only.
You will have to force your EXE project to run in 32-bit mode so it can use that C++ DLL. Project + Properties, Build tab, Platform Target = x86.
You may want to take a look at this article it explains why it is not possible, in short since you are dealing with pointers when accessing unmanaged code.
To keep you main project as Any Cpu, you need to supply both 32 and 64 bit version of the .dll - which should be possible, seeing as you're building it from source.
You then need to supply the executable with a manifest pointing it toward to right dll verion depending on platform.
Please use .net reflection and consume objects and its methods. Instead of direct 32 bit dll reference.

Single x86-built Assembly Causing entire Assembly to execute as 32-bit

My program (a console application) references several other assemblies (many open-source libraries). I built the assembly with the "Any CPU" option set (using VS2008). When I start the assembly from a 64-bit command prompt on a Windows Server 2008 x64 machine the process always starts as a 32-bit process!
I looked through my references and it appears as though I have a reference for a 32-bit assembly referenced. Could this single reference cause the entire assembly to start as 32-bit?
Also, I use ILMerge to merge all of the referenced assemblies into a single assembly. Maybe that has something to do with it?
Could someone help me figure out what is going on here?
If you need to load a 32bit assembly, the entire process will need to be 32bit. You could target "Any CPU" for your main application, but then it will run 64bit, and fail at runtime when it tries to load the 32bit assembly.
ILMerge is smart enough to switch the main entry assembly from AnyCPU to x86 if you have an x86 assembly as part of your merge, to prevent this from being a problem.
If you want to run 64bit - you'll need to have all of the assemblies be 64bit or AnyCPU.
Yes, this is likely your problem. I would rebuild the assembly as "Any CPU".

Attempt to use DLL results in error

I am using a library (DLL) that uses the Oracle.DataAccess DLL to connect to the database.
I am doing in in C# .NET framework 3.5
When I attempt to compile, the compilation takes place, but the executable throws this error message.
Could not load file or assembly 'Oracle.DataAccess, Version=2.111.7.20, Culture=
neutral, PublicKeyToken=89b483f429c47342' or one of its dependencies. An attempt
was made to load a program with an incorrect format.
Is there some way to get around this? What could be causing this to happen?
The dll for that ODBC is likely a 32bit only dll. Are you using this on a 64bit machine? If you are, IIS 7 has an option in the application pool that will allow you to "Enable 32-Bit Applications".
One possibility: Your programm is compiled with x64 or AnyCPU on a 64bit machine but the dll has been compiled with support for x86 only.
You can overcome this if you change the plattform of your Solution (or project) to x86.
I know you can force a 64bit Assembly to run as a 32bit app with:
corflags /32bit+ Oracle.DataAccess.dll
That works because the MSIL code is not bound to a processor architecture. However I never tried it the other way:
corflags /64bit+ Oracle.DataAccess.dll
so I can't tell if this works. And I propably won't work if the dll has unmanaged dependencies.

how to call a C++ dll from C# windows application project

I have created a dll in C++ using a Class Library project in Visual Studio. I need to call a method in the dll from a C# application.
I got to know there are 2 approches. One is to add the dll project reference to C# project or use DllExport to export method. However when I tried in both ways it always gives the following error when the dll method is called in runtime.
An unhandled exception of type 'System.BadImageFormatException' occurred in TestClient.exe
Additional information: An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)
Can i know how to avoid this problem ?
Thanks in advance!
This error means that you're trying to load a 32-bit DLL into a 64-bit process or a 64-bit DLL into a 32-bit process. On Windows, the bitness of the DLL must match the bitness of the process in order for it to load correctly.
Is your native DLL 32- or 64-bit? In your C# project build settings, what platform are you targeting? If you go into the C# project properties, you can go to the Build tab and change the "Platform target" to something specific like x86 or x64 to match the platform that your native DLL was built for.
The other alternative would be to build the native DLL to match the platform of your C# application. If the C# application's platform is AnyCPU, though, it will run as 32-bit on 32-bit Windows and 64-bit on 64-bit Windows. Because of this, you would need both a 32- and 64-bit version of your native DLL.
I would recommend setting your C# application's platform to something specific (x86, x64) and then change your native DLL's platform to match.

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