I built an application that used some extrnal libraries, Like Tag-lib, Naudio and Windows Media Player.
So they add me to my solution (in the same folder as my EXE file), some DLLs.
I wanted to embed those DLLs to my EXE file, so I looked at the internet and found some options.
The best answer I found was this:
Embedding DLLs in a compiled executable
And it worked, but not for all of the DLLs.
It successfully embedded Naudio and Tag-Lib, But Unabled to embed Windows Media Player's DLLs.
Can anyone help me embed the Windows Media Player's DLLs to my application's EXE?
Update:
After some help (Thanks Mathieu Wybrecht) it worked.
I did everything that he said, but still it isn't working well.
The EXE file work perfectlly, I can move him and it will work.
But when I'm in the project's solution, it error me about the missing Dlls (The Dlls of WMP that Costura.Fody just embed...), and then I copy the Dll again to the folder and the error gone. It seccessed to build the solution, rebuild the solution or starting the program, the DLLs Disapear again (embed to the EXE) and the error comes up again...
Your question is not clear. What do you mean by "when I started to use Windows Media Player, it added a DLL file, and now it doesn't ..."
Where did "it" add a DLL file?
What is "it" ? Your application? Windows Media Player?
What DLL was added?
If the problem is that you want to embed one more DLL in your exe, follow the how-to you found about Costura.Fody.
If the problem occurs at run time, ensure that all embedded DLL don't try to load more dependencies. You can check for their dependencies using "Dependency Walker", it exists for x86 and x64 platform.
Edit: you edited your question, and now I'm back to edit my answer too :)
So, you succeeded to embed few DLL but not every one of them. It can be related to some of following reasons:
Some of them are native DLL (you have to follow a particular process to embed) : you may refer to Fody/Costura unmanaged assemblies and Fody/Costura Native Libraries
For some of them, Reference in your project are maybe not marked as "Copy Local = true" and/or not considered as "Embeded Resources" for some reason
Maybe your library is correctly embedded but still present in your output directory for you may not have installed the clean-output target ?
take a look at Clean output directory
Or you may face another problem that is more specific, try to get a look at Fody/Costura issues, you may find a reason for which your desired libraries are not embedded.
Related
I have a dll library with unmanaged C++ API code I need to use in my .NET 4.0 application. But every method I try to load my dll I get an error:
Unable to load DLL 'MyOwn.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
I have read and tried several solutions I have found on the internet. Nothing works..
I have tried using following methods:
[DllImport("MyOwn.dll", CallingConvention = CallingConvention.Cdecl)]
[return: MarshalAs((UnmanagedType.I4))]
public static extern Int32 MyProIni(string DBname, string DBuser_pass,
string WorkDirectory, ref StringBuilder ErrorMessage);
When I tried following this article and when I run this example (from the downloaded code) it runs without a problem (the dll used is in the bin/debug folder)
I have copied my dll (along with all the files the it depends on into my bin folder).
I also tried this approach but got the same error:
[DllImportAttribute(MyOwnLibDllPath, EntryPoint="TMproIni")]
[return: MarshalAs(UnmanagedType.I4)]
public static extern int MyproIni(string DBname, string DBuser_pass,
string WorkDirectory, ref StringBuilder ErrorMessage);
Any suggestions?
From what I remember on Windows the search order for a dll is:
Current Directory
System folder, C:\windows\system32 or c:\windows\SysWOW64 (for 32-bit process on 64-bit box).
Reading from the Path environment variable
In addition I'd check the dependencies of the DLL, the dependency walker provided with Visual Studio can help you out here, it can also be downloaded for free: http://www.dependencywalker.com
You can use the dumpbin tool to find out the required DLL dependencies:
dumpbin /DEPENDENTS my.dll
This will tell you which DLLs your DLL needs to load. Particularly look out for MSVCR*.dll. I have seen your error code occur when the correct Visual C++ Redistributable is not installed.
You can get the "Visual C++ Redistributable Packages for Visual Studio 2013" from the Microsoft website. It installs c:\windows\system32\MSVCR120.dll
In the file name, 120 = 12.0 = Visual Studio 2013.
Be careful that you have the right Visual Studio version (10.0 = VS 10, 11 = VS 2012, 12.0 = VS 2013...) right architecture (x64 or x86) for your DLL's target platform, and also you need to be careful around debug builds. The debug build of a DLL depends on MSVCR120d.dll which is a debug version of the library, which is installed with Visual Studio but not by the Redistributable Package.
The DLL has to be in the bin folder.
In Visual Studio, I add the dll to my project NOT in References, but "Add existing file". Then set the "Copy to Output Directory" Property for the dll to "Copy if newer".
This is a 'kludge' but you could at least use it to sanity-test:
Try hard-coding the path to the DLL in your code
[DllImport(#"C:\\mycompany\\MyDLL.dll")]
Having said that; in my case running dumpbin /DEPENDENTS as suggested by #anthony-hayward, and copying over 32-bit versions of the DLLs listed there into my working directory solved this problem for me.
The message is just a bit misleading, becuase it isn't "my" dll that can't be loaded - it's the dependencies
Try to enter the full-path of the dll.
If it doesn't work, try to copy the dll into the system32 folder.
"Unable to load DLL 'xxx.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)" means the file CAN be found BUT it's not able to load it. Try to copy the DLL file to the root folder of your application, some DLL libraries need to be available in the root folder of the application in order for it to work. Or check if there are any other depending DLL files required by it.
"Cannot find DLL 'xxx.dll': ..." means the file CANNOT be found. Try to check the path. For example, [DllImport(#"\Libraries\Folder\xxx.dll")]
Ensure that all dependencies of your own dll are present near the dll, or in System32.
Turn on the fusion logging, see this question for lots of advice on how to do that. Debugging mixed-mode apps loading problems can be a right royal pain. The fusion logging can be a big help.
Make sure you set the Build Platform Target to x86 or x64 so that it is compatible with your DLL - which might be compiled for a 32 bit platform.
There is one very funny thing (and has a technical relevance) which might waste your hours so thought of sharing it here -
I created a console application project ConsoleApplication1 and a class library project ClassLibrary1.
All the code which was making the p/invoke was present in ClassLibrary1.dll. So before debugging the application from visual studio I simply copied the C++ unmanaged assembly (myUnmanagedFunctions.dll) into the \bin\debug\ directory of ClassLibrary1 project so that it can be loaded at run-time by the CLR.
I kept getting the
Unable to load DLL
error for hours. Later on I realized that all such unmanaged assemblies which are to be loaded need to be copied into the \bin\debug directory of the start-up project ConsoleApplication1 which is usually a win form, console or web application.
So please be cautious the Current Directory in the accepted answer actually means Current Directory of main executable from where you application process is starting. Looks like an obvious thing but might not be so at times.
Lesson Learnt - Always place the unamanaged dlls in the same directory as the start-up executable to ensure that it can be found.
I had the same problem when I deployed my application to test PC. The problem was development PC had msvcp110d.dll and msvcr110d.dll but not the test PC.
I added "Visual Studio C++ 11.0 DebugCRT (x86)" merge module in InstalledSheild and it worked. Hope this will be helpful for someone else.
In my case one unmanaged dll was depending on another which was missing. In that case the error will point to the existing dll instead of the missing one which can be really confusing.
That is exactly what had happen in my case. Hope this helps someone else.
If the DLL and the .NET projects are in the same solution and you want to compile and run both every time, you can right click the properties of the .NET project, Build events, then add something like the following to Post-build event command line:
copy $(SolutionDir)Debug\MyOwn.dll .
It's basically a DOS line, and you can tweak based on where your DLL is being built to.
I think your unmanaged library needs a manifest.
Here is how to add it to your binary. and here is why.
In summary, several Redistributable library versions can be installed in your box but only one of them should satisfy your App, and it might not be the default, so you need to tell the system the version your library needs, that's why the manifest.
Setup: 32-bit Windows 7
Context: Installed a PCI-GPIB driver that I was unable to communicate through due to the aforementioned issue.
Short Answer: Reinstall the driver.
Long Answer:
I also used Dependency Walker, which identified several missing dependency modules. Immediately, I thought that it must have been a botched driver installation. I didn't want to check and restore each missing file.
The fact that I was unable to find the uninstaller under Programs and Features of the Control Panel is another indicator of bad installation. I had to manually delete a couple of *.dll in \system32 and registry keys to allow for driver re-installation.
Issue fixed.
The unexpected part was that not all dependency modules were resolved. Nevertheless, the *.dll of interest can now be referenced.
I have come across the same problem, In my case I had two 32 bit pcs.
One with .NET4.5 installed and other one was fresh PC.
my 32-bit cpp dll(Release mode build) was working fine with .NET installed PC but Not with fresh PC where I got the below error
Unable to load DLL 'PrinterSettings.dll': The specified module could not be
found. (Exception from HRESULT: 0x8007007E)
finally,
I just built my project in Debug mode configuration and this time my
cpp dll was working fine.
Also faced the same problem when using unmanaged c/c++ dll file in c# environment.
1.Checked the compatibility of dll with 32bit or 64bit CPU.
2.Checked the correct paths of DLL .bin folder, system32/sysWOW64 , or given path.
3.Checked if PDB(Programme Database) files are missing.This video gives you ans best
undestand about pdb files.
When running 32-bit C/C++ binary code in 64bit system, could arise this because of platform incompatibility. You can change it from Build>Configuration manager.
I faced the same problem when import C++ Dll in .Net Framework +4, I unchecked Project->Properties->Build->Prefer 32-bit and it solved for me.
It has nothing to do with dependencies if you checked all dependencies and you know you got them all, it has nothing to do with the file being in the wrong directory either or incorrect ARGUMENTS passed to dll, the DLL Fails to load using LoadLibrary itself.. you could check the address returned from LoadLibrary is always 0x0000000 (not loaded).
I couldn't figure this error out either it worked fine on Windows 7, but on Windows 10 it doesn't work. I fixed the problem though it had nothing to do with missing dependencies or Runtime redistributable packs.
The problem was I had to pack the DLL with upx and it started working again.
Something with the file being unpacked and compiled on old Windows XP operating system created a bad PE Header or Bad file format or something, but packing it with UPX did the trick works fine now and the DLL got 3x smaller haha.
I got this error for one C++ project in our solution, and only on our buildmaster's machine. The rest of us could build it with no problem.
In our case it was because that particular project had <WindowsTargetPlatformVersion> in the .vcxproj file set to "10.0" vs. "10.0.18362.0" as in all our other C++ projects.
Not specifying the entire SDK version number seems to have allowed MSBuild to choose the newest(?) SDK and associated build tools.
Our buildmaster likely had the remnants of a newer SDK on his machine, and MSBuild was trying to use it (and thus RC.exe was not found).
In any case, bringing up the project's property page and changing Configuration Properties > General > Windows SDK Version to "10.0.18362.0" (or whichever specific version of the SDK you have installed) for all of the project's configurations/platforms did the trick.
I have a dll library with unmanaged C++ API code I need to use in my .NET 4.0 application. But every method I try to load my dll I get an error:
Unable to load DLL 'MyOwn.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
I have read and tried several solutions I have found on the internet. Nothing works..
I have tried using following methods:
[DllImport("MyOwn.dll", CallingConvention = CallingConvention.Cdecl)]
[return: MarshalAs((UnmanagedType.I4))]
public static extern Int32 MyProIni(string DBname, string DBuser_pass,
string WorkDirectory, ref StringBuilder ErrorMessage);
When I tried following this article and when I run this example (from the downloaded code) it runs without a problem (the dll used is in the bin/debug folder)
I have copied my dll (along with all the files the it depends on into my bin folder).
I also tried this approach but got the same error:
[DllImportAttribute(MyOwnLibDllPath, EntryPoint="TMproIni")]
[return: MarshalAs(UnmanagedType.I4)]
public static extern int MyproIni(string DBname, string DBuser_pass,
string WorkDirectory, ref StringBuilder ErrorMessage);
Any suggestions?
From what I remember on Windows the search order for a dll is:
Current Directory
System folder, C:\windows\system32 or c:\windows\SysWOW64 (for 32-bit process on 64-bit box).
Reading from the Path environment variable
In addition I'd check the dependencies of the DLL, the dependency walker provided with Visual Studio can help you out here, it can also be downloaded for free: http://www.dependencywalker.com
You can use the dumpbin tool to find out the required DLL dependencies:
dumpbin /DEPENDENTS my.dll
This will tell you which DLLs your DLL needs to load. Particularly look out for MSVCR*.dll. I have seen your error code occur when the correct Visual C++ Redistributable is not installed.
You can get the "Visual C++ Redistributable Packages for Visual Studio 2013" from the Microsoft website. It installs c:\windows\system32\MSVCR120.dll
In the file name, 120 = 12.0 = Visual Studio 2013.
Be careful that you have the right Visual Studio version (10.0 = VS 10, 11 = VS 2012, 12.0 = VS 2013...) right architecture (x64 or x86) for your DLL's target platform, and also you need to be careful around debug builds. The debug build of a DLL depends on MSVCR120d.dll which is a debug version of the library, which is installed with Visual Studio but not by the Redistributable Package.
The DLL has to be in the bin folder.
In Visual Studio, I add the dll to my project NOT in References, but "Add existing file". Then set the "Copy to Output Directory" Property for the dll to "Copy if newer".
This is a 'kludge' but you could at least use it to sanity-test:
Try hard-coding the path to the DLL in your code
[DllImport(#"C:\\mycompany\\MyDLL.dll")]
Having said that; in my case running dumpbin /DEPENDENTS as suggested by #anthony-hayward, and copying over 32-bit versions of the DLLs listed there into my working directory solved this problem for me.
The message is just a bit misleading, becuase it isn't "my" dll that can't be loaded - it's the dependencies
Try to enter the full-path of the dll.
If it doesn't work, try to copy the dll into the system32 folder.
"Unable to load DLL 'xxx.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)" means the file CAN be found BUT it's not able to load it. Try to copy the DLL file to the root folder of your application, some DLL libraries need to be available in the root folder of the application in order for it to work. Or check if there are any other depending DLL files required by it.
"Cannot find DLL 'xxx.dll': ..." means the file CANNOT be found. Try to check the path. For example, [DllImport(#"\Libraries\Folder\xxx.dll")]
Ensure that all dependencies of your own dll are present near the dll, or in System32.
Turn on the fusion logging, see this question for lots of advice on how to do that. Debugging mixed-mode apps loading problems can be a right royal pain. The fusion logging can be a big help.
Make sure you set the Build Platform Target to x86 or x64 so that it is compatible with your DLL - which might be compiled for a 32 bit platform.
There is one very funny thing (and has a technical relevance) which might waste your hours so thought of sharing it here -
I created a console application project ConsoleApplication1 and a class library project ClassLibrary1.
All the code which was making the p/invoke was present in ClassLibrary1.dll. So before debugging the application from visual studio I simply copied the C++ unmanaged assembly (myUnmanagedFunctions.dll) into the \bin\debug\ directory of ClassLibrary1 project so that it can be loaded at run-time by the CLR.
I kept getting the
Unable to load DLL
error for hours. Later on I realized that all such unmanaged assemblies which are to be loaded need to be copied into the \bin\debug directory of the start-up project ConsoleApplication1 which is usually a win form, console or web application.
So please be cautious the Current Directory in the accepted answer actually means Current Directory of main executable from where you application process is starting. Looks like an obvious thing but might not be so at times.
Lesson Learnt - Always place the unamanaged dlls in the same directory as the start-up executable to ensure that it can be found.
I had the same problem when I deployed my application to test PC. The problem was development PC had msvcp110d.dll and msvcr110d.dll but not the test PC.
I added "Visual Studio C++ 11.0 DebugCRT (x86)" merge module in InstalledSheild and it worked. Hope this will be helpful for someone else.
In my case one unmanaged dll was depending on another which was missing. In that case the error will point to the existing dll instead of the missing one which can be really confusing.
That is exactly what had happen in my case. Hope this helps someone else.
If the DLL and the .NET projects are in the same solution and you want to compile and run both every time, you can right click the properties of the .NET project, Build events, then add something like the following to Post-build event command line:
copy $(SolutionDir)Debug\MyOwn.dll .
It's basically a DOS line, and you can tweak based on where your DLL is being built to.
I think your unmanaged library needs a manifest.
Here is how to add it to your binary. and here is why.
In summary, several Redistributable library versions can be installed in your box but only one of them should satisfy your App, and it might not be the default, so you need to tell the system the version your library needs, that's why the manifest.
Setup: 32-bit Windows 7
Context: Installed a PCI-GPIB driver that I was unable to communicate through due to the aforementioned issue.
Short Answer: Reinstall the driver.
Long Answer:
I also used Dependency Walker, which identified several missing dependency modules. Immediately, I thought that it must have been a botched driver installation. I didn't want to check and restore each missing file.
The fact that I was unable to find the uninstaller under Programs and Features of the Control Panel is another indicator of bad installation. I had to manually delete a couple of *.dll in \system32 and registry keys to allow for driver re-installation.
Issue fixed.
The unexpected part was that not all dependency modules were resolved. Nevertheless, the *.dll of interest can now be referenced.
I have come across the same problem, In my case I had two 32 bit pcs.
One with .NET4.5 installed and other one was fresh PC.
my 32-bit cpp dll(Release mode build) was working fine with .NET installed PC but Not with fresh PC where I got the below error
Unable to load DLL 'PrinterSettings.dll': The specified module could not be
found. (Exception from HRESULT: 0x8007007E)
finally,
I just built my project in Debug mode configuration and this time my
cpp dll was working fine.
Also faced the same problem when using unmanaged c/c++ dll file in c# environment.
1.Checked the compatibility of dll with 32bit or 64bit CPU.
2.Checked the correct paths of DLL .bin folder, system32/sysWOW64 , or given path.
3.Checked if PDB(Programme Database) files are missing.This video gives you ans best
undestand about pdb files.
When running 32-bit C/C++ binary code in 64bit system, could arise this because of platform incompatibility. You can change it from Build>Configuration manager.
I faced the same problem when import C++ Dll in .Net Framework +4, I unchecked Project->Properties->Build->Prefer 32-bit and it solved for me.
It has nothing to do with dependencies if you checked all dependencies and you know you got them all, it has nothing to do with the file being in the wrong directory either or incorrect ARGUMENTS passed to dll, the DLL Fails to load using LoadLibrary itself.. you could check the address returned from LoadLibrary is always 0x0000000 (not loaded).
I couldn't figure this error out either it worked fine on Windows 7, but on Windows 10 it doesn't work. I fixed the problem though it had nothing to do with missing dependencies or Runtime redistributable packs.
The problem was I had to pack the DLL with upx and it started working again.
Something with the file being unpacked and compiled on old Windows XP operating system created a bad PE Header or Bad file format or something, but packing it with UPX did the trick works fine now and the DLL got 3x smaller haha.
I got this error for one C++ project in our solution, and only on our buildmaster's machine. The rest of us could build it with no problem.
In our case it was because that particular project had <WindowsTargetPlatformVersion> in the .vcxproj file set to "10.0" vs. "10.0.18362.0" as in all our other C++ projects.
Not specifying the entire SDK version number seems to have allowed MSBuild to choose the newest(?) SDK and associated build tools.
Our buildmaster likely had the remnants of a newer SDK on his machine, and MSBuild was trying to use it (and thus RC.exe was not found).
In any case, bringing up the project's property page and changing Configuration Properties > General > Windows SDK Version to "10.0.18362.0" (or whichever specific version of the SDK you have installed) for all of the project's configurations/platforms did the trick.
am create a desktop application using wpf. am installd newtonsoft.json(using package manager) for json parsing. after am successfully build and run my application.
then iam copy the appliction.exe from project source > bin > debug to my Destop. then am attempt to run exe from Desktop, but i got an error message
like this
could not load file or assembly 'newtonsoft.json' ..... system cannot find
the path
what is the issue? any missing
The exe needs to be able to link to the dll when you run it. That's why it works in your debug folder (the newtonsoft dll is there if you look), while it's presumably not in your desktop.
You can either:
1) Make sure the dll is included with the exe (copy it to your desktop, for example). If you distribute the exe in a zip file, just include the dll. If you use an installer, make sure it also installs the dll to the same folder.
OR
2) ILMerge the DLL directly into your exe - this means the exe contains the entire DLL and will always be able to find it. There are NuGet packages that can do this for you autonatically. Try adding "MSBuild.ILMerge.Task" via NuGet, and then build your project again.
(There are other solutions but they're generally terrible, like PATH, so I'm not going to explain how they work).
Personally, I'd usually recommend the former - just include the DLL. Look inside folders where you have software on your PC (e.g. most folders in Program Files) - you'll see that's how it's usually done, with DLLs installed as separate files. ILMerge can get messy if you don't know what you're doing and you start doing weird things with your DLLs.
My C++ app was required to communicate with a web application. Since writing in C++ was hard I wrote the web application client in C# (DLL), COM enabled it, and called it from C++ app and it worked.
But the C++ app can be installed on a server PC, its folder shared over a network, mapped to a drive on a client PC, and run from there. When I tried running so, it doesn't run because it is expecting the C# DLL to be registered on the client PC. I would like to avoid it. I would like to keep them both on the server. Is it possible to do it using registration-free COM? If yes, can the C# DLL (and its dependent DLLs) be placed in a folder different to the C++ EXE folder?
I see this is an outdated post. Hope you had found out a solution or a workaround. Anyhow, I shall answer as it may help someone with the same problem.
Is it possible to do it using registration-free COM?
Yes, it is. Follow this MSDN article. You will have to create a manifest for the c# com dll and embed the manifest into it. Which would be with the help of a RT_MANIFEST resource. That article is a little outdated, so you may face problem with .net framework version. If you did, you will need to specify the .net framework version in your machine. You can simply replace the clrclass line with this :
<clrClass
clsid="{16AD5303-E154-44B4-A72B-C129859714AD}"
progid="SideBySide.SideBySide"
threadingModel="Both"
name="SideBySide.SideBySideClass"
runtimeVersion="v4.0.30319" >
can the C# DLL (and its dependent DLLs) be placed in a folder
different to the C++ EXE folder?
Yes, it can be. But I wouldn't recommend it. According to this resource, the assembly loader searches for assembly manifests in the following order :
Side-by-side searches the WinSxS folder.
\\<appdir>\<assemblyname>.DLL
\\<appdir>\<assemblyname>.manifest
\\<appdir>\<assemblyname>\<assemblyname>.DLL
\\<appdir>\<assemblyname>\<assemblyname>.manifest
The above locations are respective to the application (appdir). If you want your dll to be elsewhere, then you can use the file element of the assembly manifest (the name attribute can include a path), see here for more details and other elements.
Hope this helps someone.
I have a code sample that's supposed to detect my canon 550d digital camera so I can control the camera from the pc.
I just downloaded the source files from here:
http://www.codeproject.com/Articles/17344/A-wrapper-for-the-canon-CDSDK-and-PRSDK-for-remote?fid=379739&df=90&mpp=25&noise=3&prof=False&sort=Position&view=Quick&spc=Relaxed&fr=1#xx0xx
I created a new project in Visual Studio 2012 Pro; my pc is running Windows 8 64bit.
I added all the .cs files and also copied all the dll files I downloaded from the Canon website after registering.
The first time I ran the program and clicked on the connect button, I got an exception that a dll is missing. Since there is no way to add the dlls as referenced, I copied them to the Debug directory.
The missing dll was PRSDK.dll, so I found and downloaded the dll, and copied it.
Now when I click on the connect button, I get a different exception:
BadImageFormatException: An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)
The exception is in the file Camera.cs, on the line:
err = prAPI.PR_StartSDK();
I googled for this exception and found that some people have changed the project platform and target to x86, so I tried it - I tried changing it to x86, x64, AnyCpu, everything, but it didn't help.
Maybe the PRSDK.dll file is old and not useable in Windows 8?
This is a link to my project/solution in my SkyDrive, if someone can please download it and try to run it on his machine and maybe find a solution?
https://skydrive.live.com/redir?resid=EB1C71C44C3976D5!201&authkey=!AErpIgyllPAgH9w
The project called: Canon_Camera_Control
OK, I downloaded your project and found the problem.
Your DLL files are wrong!
They are not even DLL actually, they are html files with the .dll extension. Apparently you tried to download them from some webpage but didn't succeed.
Try redownloading it or obtain the SDK from official (Canon) sources.
You must have missed something. The error is definitely the one that states that the platform of your project and the one of the external dll don't match.
Maybe you changed the "Active solution platform" but not the "Project platform".
One thing that tripped me up regarding exactly this, not too long ago: check to make sure (Build->Configuration Manager) that in your solution, when you change the solution's platform to x86, the platform of your actual project in that dialog is actually set to x86. Sometimes VS is dumb, and leaves it as Any CPU (great if all your code and all your third-party dlls are managed, not so great if you're calling, for instance, a wrapper to an unmanaged camera dll.)
It's possible something totally unrelated is going on, but every time I've seen that error it's because you're running as x86/x64 and loading an unmanaged dll that's of the other platform type.
One reason is that you might be trying to load a 32-bit assembly into a 64-bit application. This can happen when you have the Any CPU platform selected.
On my blog I outline this issue more with screenshots on how you can change it
but basically you can set your project it always compile in 32 bit mode.