Error while 32-bit C# program calling 32-bit C++ DLL

Question

I called a 32-bit C++ DLL from a 32-bit C# application, resulting in the error: "HRESULT: 0x8007000B". I used tools, such as sigcheck and "dumpbin /headers" to confirm the application and DLL are both 32-bit ones. I googled all relative articles and they are saying this is due to a 64-bit application calling 32-bit DLL. I confirm the two are 32-bit ones. So, what can I do to check and figure it out. My IDE is VS 2019 on Windows 10. I referred source codes and take as base from : https://www.codeproject.com/Articles/843839/Calling-All-Stations My calling portions at C# program and DLL codes are cut and paste from the above sample. I also built and tested the sample successfully. So, I got confused why it doesn't work at my programs because I follow the same structure at my project.

Amit Gupta · Answer

Do check, if the dll is build with x64 bit architecture then it can't be executed on x86 bit machines no matter what project type (32/64 bit) do you have. Try calling it on 64 bit machines if it rums then you are good to go

Sachin Singh · Answer

The only reason for badimageformat exception is non compatible versions of two dlls , there is definitely some dlls which are compiled against 64 bit that's causing the issue. also test with downgrade your .net version to older version.

Stan Huang · Answer

I talked with the original author of the C# application program and know that it linked several other 64-bit DLLs. That could be the reason why the application program can't load my 32-bit DLL. His linked DLLs causes the application program to run at 64-bit mode, although the 'dumpbin /headers' shows the application program is a 32-bit one. So, I tried to re-built the C# application and C++ DLL in 64-bit and then they two can work successfully.

Stan Huang · Answer

I would like to try another alternative: build both (C# application & C++ DLL) into 64-bit ones. I built 64-bit application successfully. But when I changed DLL project's "Target Machine" configuration to x64 and then rebuilt it, I got the error: fatal error LNK1112: module machine type 'x86' conflicts with target machine type 'x64' > What did I miss to change the configuration before building 64-bit DLL? > I found DLL property's 'Platform' having only Win32 & ActiveWin32. Why is there no x64 option?

Stan Huang · Answer

I posted the screenshot of the Reference Manager of the C# application. The DLLs which I linked are all 32-bit ones. I also used a tool (VS's 'dumpbin') to confirm it. What else checking can I do furtherly?

Stan Huang · Answer

same thing, no change. The same error occurred.

Sachin Singh · Answer

Right click on your project -->Properties--->Build tab--->Performance target here change the target from any cpu to x86. recompile and test.