Develop Reference

Problem using Global Hooks in Windows Forms [duplicate]

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.

Could not load file or assembly (DarkRift)

I've been struggling with a problem in Unity and I would appreciate it if anyone can help me.
I'm using a package called DarkRift, which is used for networking and connecting clients with a server (provided by DarkRift). In order to work with the DarkRift server, I need to write plugins. A plugin is basically a visual studio project, compiled to .dll file, then that file is copied to a certain directory on the server-side.
I've been working with DarkRift for some time now and have done so much with it. It was working perfectly! However, I needed to work with Firestore package from Google.
Hence, I created another plugin, installed Firestore (and every package needed), wrote some simple code using one of Firestore's functions, compiled the project, copied .dll to the server, then ran the server. The problem is whenever I run the server (.exe file), I get an error that says: "Could not load file or assembly 'Google.Cloud.Firestore, Version=1.0.0.0, ...' or one of its dependencies."
I get this error when I use any of Firestore's functions. However, if I just include the package (using Google.Cloud.Firestore;) without using any of its functions, I don't get any error. I googled this problem and looked everywhere and could not solve it.
Thanks!

Firestore is distributed as a Nuget package, which indeed has dependencies.
Have you also copied all those dependencies to the server?
It might also be a framework incompatibility.
To get more details about this kind of problem, you can register a logging event handler on AppDomain.AssemblyResolve, which fires when assembly resolution fails.
You can also use tools like dnSpy to dig into the problematic assembly - it shows you all sorts of metadata and it can decompile the CIL, which is invaluable for debugging strange behavior in third party code.
Assembly loading is kind of slow in .Net, so it only loads them when needed.
Hence the resolution does not fail when no code references the assembly.

Identifying problematic dependencies in C++/CLI project

My application compiles fine, but I get the following runtime error:
System.IO.FileNotFoundException was unhandled
HResult=-2147024770
Message=Could not load file or assembly {Wrapper} or one of its dependencies. The specified module could not be found.
The reference to Wrapper in the calling Application looks correct. The Wrapper dll exists in the correct location.
This project used to build and run on someone else's system, I saw it demonstrated several times. That person/computer is no longer available. Some paths of some dependencies have changed since the last time it was successfully built and run, I have fixed all compile errors related to this.
Just to clarify my project structure:
Digraph G
{
App [ label = "My C# Application"]
Wrapper [ label = "C++/CLI Wrapper"]
Lib [ label = "C++ Library"]
Dll [ label = "My helper C# DLL"]
CDep [ label = "Series of deep C++ dependencies managed \n by CMake for Lib, hard coded relative paths for Wrapper."]
App->Wrapper->Lib->CDep;
App->Dll->Wrapper->CDep;
}
Wrapper is a C++/CLI wrapper around a C++ library. The error is triggered when we try to load a class in the Application that has a using statement for the Wrapper.
Wrapper does have a lot of dependencies, but the error message does not indicate which dependency is problematic. This is a large, complicated system, most of which is built by other teams. The C++ components use CMake to get all the dependencies correct, but CMake does not natively support C#.
I tried using fuslogvw to find the binding error, but it showed me absolutely nothing until I changed settings to include all binds, and then it only showed successful binds.
http://msdn.microsoft.com/en-us/library/e74a18c4(v=vs.100).aspx
The paths are long, but not over 256 characters.
I had a warning in the compile for Dll (see graph above):
Warning 1 There was a mismatch between the processor architecture of the project being built "MSIL" and the processor architecture of the reference "{cli_wrapper.dll}", "AMD64". 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.
In Configuration Manager, the Dll is building for Platform "Any CPU" and Wrapper is building for "x64". I changed the dll to x64. I still get the runtime error.
Could not load file or assembly or one of its dependencies
Performed a clean, deleted build directory contents. No change.
Re-opened Visual Studio. No change.
Tried changing assembly name, default namespace, and project name to match. No change.
Could not load file or assembly 'xxx' or one of its dependencies. An attempt was made to load a program with an incorrect format
I believe we have to compile for 64 bit. We are dependant on a 64 bit C++ library.
Could not load file or assembly ... The parameter is incorrect
I am local administrator.
How to enable assembly bind failure logging (Fusion) in .NET
Tried the registry settings, but they appear to just be fuslogvw settings. No improvement in available log data.
Many other similar questions had ASP or service install specific answers.

I found the problem. There was more than one version of the library available to me, and I was using the include files from one version and the compiled library of the other. Dependancy Walker was key to finding which library had the problem, and if Aschratt had posted that as an answer rather than as a comment I would have accepted his answer.

I had the same error with a similar project earlier this week. First, when using C++/CLI, "Any CPU" doesn't exist. I had to build both for x86 to get through things.
Also, though my wrapper's dependencies were satisfied, it's the wrapper's exception that is caught by the CLR so it claims that the wrapper is missing a dependency. I was actually missing a dependency for the C++ DLL my wrapper wrapped (in my case, it was just a matter of forgetting to drop SDL2.dll and OpenAL32.dll in my new "Release" configuration output folder... I'd previously only worked with the Debug configuration where I'd already dropped those DLLs.
If you're positive you've got your wrapper's dependencies worked out, I'd recommend using Dependency Walker to check out the native DLL's dependencies. You could use Assembly.GetReferencedAssemblies with an outside script/program to double-check your wrapper as well (or ILSpy: http://ilspy.net/).
Last but not least, take a look at this: http://www.codeproject.com/Articles/442784/Best-gotchas-of-Cplusplus-CLI. He details the first two recommendations I made as well as some others.
Good luck!

One alternate root cause I've been running into quite a bit later, is that the application I'm working on uses impersonation, and the impersonated user does not have permissions to the GAC or to the folder that some dlls are in. You need to either give that user permissions, or change the way you do impersonation to load the dependencies before impersonation starts.

Launching C# WPF from Java causes FileNotFoundExceptions

I have a existing Java Project which needs functionality from a SDK written in C#. It should open a WPF Window and send the information back to Java on close.
For a basic connection of those two worlds i created a Java Project ("DotNetCaller") calling native functions. These are implemented in a C++/CLI Project ("DotNetBridge") which calls the C# Project ("DotNetApplication").
I already can set Strings from Java in C# and callback from C# to Java.
But as soon as i add a WPF Window and try to launch it with:
Application app = new Application();
app.Run(new DotNetWindow());
in a STA Thread it crashes.
The DotNetApplication doesnt find mscorlib.resources, after i provide the DLL, PresentationFramework.resources is missing and if i provide that, the DotNetApplication.resource is missing (which i cant provide).
If i call the DotNetApplication alone or from the DotNetBridge the Window displays as expected.
Can anyone tell ma what i'm really missing here?
Thanks
Edit:
I looked at this example once more and tried to adapt it to my needs.
I have set the dll directory of the ResolveEventHandler to the .NET dir in "Referenced Assemblies"
C:\Program Files (x86)\Reference
Assemblies\Microsoft\Framework.NETFramework\v4.0
and added a Window in C#.
It failed aswell but with a new exception in the C++ part rather than C#.
The ResolveHandler gets called with an empty argument causing an uncatchable exception in mscorelib.
I added a check if the String is empty and this basic approach works fine now.
I'm still unsure if i have the correct approach for this, so feel free to contribute.

Your AppDomain::AssemblyResolve handler probably needs to be overhauled and based on your own understanding of what you want to do. There is some guidance here. The basic rule is that you return nullptr for requests that you can't handle.
But first you have to plan the locations in which you want to deploy (and/or debug) your assemblies. A simple layout would be to put all of the assemblies that your JNI DLL depends on in the same folder as the JNI DLL (with the exception of any that will be installed in the GAC). You can then use its location to satisfy resolution requests. But remember to return nullptr if no file containing a manifest for an assembly with the requested name is present there. (This is likely the case with your ".resources" requests. If there isn't one it's okay unless you know otherwise.)
I'd be a little surprised if an assembly in a Reference Assemblies folder wasn't also in the GAC—but it'd be up to the assembly provider. Reference Assemblies is for design and build tools (e.g. Visual Studio). (The old way was for each folder that had assemblies in it to be registered for each version of Visual Studio so the assemblies could be used for design and build.) If a dependency is not in the GAC, you can use the "Copy Local" property on the reference to make it available for debugging.
You might find the Assembly Binding Log Viewer useful while designing and troubleshooting. With it you can see all the folders and extensions that are tried before giving over to calling the AppDomain::AssemblyResolve handler chain. (Disable logging when you are done.)

Assembly references won't resolve properly on our build server

We code in C# using VS2008 SP1. We have a server that runs Team System Server 2008 which we use for source control, tasks etc. The server is also our build machine for Team Build. This has been working just fine for a long time. Untill now. We get these error messages when trying to build one of our projects that has a reference to one external assembly (this happens both via Team Build, and when logging on physically and doing a regular build via Visual Studio):
C:\WINDOWS\Microsoft.NET\Framework\v3.5\Microsoft.Common.targets
: warning MSB3246: Resolved file has a
bad image, no metadata, or is
otherwise inaccessible. Could not load
file or assembly 'C:\Program
Files\Syncfusion\Essential
Studio\7.1.0.21\Assemblies\3.5\Syncfusion.XlsIO.Base.dll'
or one of its dependencies. The module
was expected to contain an assembly
manifest.
C:\Program
Files\MSBuild\Microsoft\VisualStudio\v9.0\ReportingServices\Microsoft.ReportingServices.targets(24,2):
error MSB4062: The
"Microsoft.Reporting.RdlCompile" task
could not be loaded from the assembly
Microsoft.ReportViewer.Common,
Version=9.0.0.0, Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a. Could
not load file or assembly
'Microsoft.ReportViewer.Common,
Version=9.0.0.0, Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a' or
one of its dependencies. The module
was expected to contain an assembly
manifest. Confirm that the
declaration is correct, and that the
assembly and all its dependencies are
available.
The referenced component
'Syncfusion.XlsIO.Base' could not be
found.
These errors are for one project with one problematic assembly reference. When I try to build the entire solution there are of course many more errors because of this one. And there are two other projects that has the same problem with other assembly references. I have a list of the referenced assemblies that VS can't seem to resolve:
Microsoft.ReportViewer.Common
Microsoft.ReportViewer.WinForms
Syncfusion.Compression.Base
Syncfusion.Core
Syncfusion.XlsIO.Base
The Syncfusion assemblies are from a 3rd-party component package. The other two are related to the Microsoft ReportViewer component.
The references has been added via the Add Reference window, in the .NET tab, so I don't think there is anything suspicious about that. In the properties window for the assembly reference, there is no value in Culture, Description, Path, Runtime Version or Strong Name. Version says 0.0.0.0 and Resolved is False. I guess it is pretty obvious that VS cant resolve the reference. My question is why??? I've scratched my head a lot over this one. This only occurs on the server, the solution builds just fine on both my machine, and my coworkers machine. The assembly reference properties are fine on our machines.
I have tried uninstalling the 3rd-party component (on the server of course), and then reinstalling it again. Didn't help. I tried to repair the VS2008 installation. Didn't help. Tried to retrieve an earlier version from source control (that I know has buildt on the server before), and I got the same error messages. I have checked file permissions, and everything appears to be in order. I am running out of ideas...
How do I solve this?
Update 16.02.2009:
I have tried to compare ildasm output of the dll on my pc and on the server (see the comment I wrote about that), and there is one small difference in a line that to me appears to be a comment. I must admit that I don't understand why there is a difference at all, so maybe someone could explain that to me?
I also tried running a virus scan on the server. Didn't help. Tried to remove the reference and then readd it by browsing to the dll on disk. Didn't work.
Update 17.03.2009:
I've found the solution! The culprit was the TruPrevent module of Panda Antivirus. After disabling the module, everything works! =)
I discovered this with the help of fuslogvw.exe and the log it generated. Googled the result, and stumbled upon this blog entry.. Hope this can help somebody else to.

Almost certainly the problem is environmental - not source related.
Some ideas ...
(i) Try disabling your anti-virus/anti-malware tools - I've seen cases where these tools (particularly Trend Micro Antivirus, for some reason) can keep a DLL file locked after (during?) scanning, interfering with compilers.
(ii) Check your PATH environment variable. Even in these modern days, the PATH variable is used to resolve some things - if this is messed up (too long, maximum length is 2048 characters IIRC) then things can be odd.
(iii) You've checked File permissions - have you checked permissions in the registry? For example, SyncFusion installs its license key in both the User and Machine hives - if the build server can't read one or the other, could cause issues.
Good luck!

It could also be that the referenced assemblies are in the GAC on the dev machine, but not on the build machine. Get it out of the GAC, into your source repository, and reference it by path.

We've had the same problem, turns out the C drive was full (only had 28MB).
Freeing space resolved the issue, even though the build happens on D.

Do you see any differences between ildasm of this file
'C:\Program Files\Syncfusion\Essential Studio\7.1.0.21\Assemblies\3.5\Syncfusion.XlsIO.Base.dll'
on your machine versus on the server?

My suspicion is that the user that the build process is under does not have access to the folder that your 3rd party control is in. Since this functions properly on your machines, it is almost certainly user/permission specific.

Your 3rd party dll may depend on unmanaged dlls. Often it's because a specific version of the VC++ Runtime Dlls are missing.
Open the Dll with the Dependency Walker http://www.dependencywalker.com/ on your server and check for missing references.

Not sure if this'll help in your case, but I did have something similar before where a dll apparently got unregistered somehow, and running regsvr32 on the dll did the trick.