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

Stan Huang

5y1.3k

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.

7 Replies

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Stan Huang5y ago
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 Huang5y ago
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 Huang5y ago
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?
Amit Gupta5y ago
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 Singh5y ago
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 Huang5y ago
same thing, no change. The same error occurred.
Sachin Singh5y ago
Right click on your project -->Properties--->Build tab--->Performance target
here change the target from any cpu to x86.
recompile and test.