Unable to load DLL 'libwkhtmltox': The specified module could not be found. When using Nuget package

When using the DinkToPdf Nuget package I get the error message below because it is looking for the libwkhtmltox DLL in the same folder the Nuget package DLL is in. For me using VS 2017 on Windows 10 this is:

%UserProfile%\.nuget\packages\dinktopdf\1.0.8\lib\netstandard1.6

When I either manually copy the correct libwkhtmltox DLL to this folder or include the source of the DinkToPdf project into my solution I no longer get this error. By including the project source into my solution the DinkToPdf DLL is then compiled into my output folder where it then also successfully finds the libwkhtmltox DLL.

Is it possible to resolve this issue without having to use the project source or regsvr32.exe? I see that TuesPechkin has an IDeployment interface to address this issue (see: https://github.com/tuespetre/TuesPechkin/issues/57). Is it possible to do something similar in DinkToPdf?

System.AggregateException: One or more errors occurred. (Unable to load DLL 'libwkhtmltox': The specified module could not be found. (Exception from HRESULT: 0x8007007E)) ---> System.DllNotFoundException: Unable to load DLL 'libwkhtmltox': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
   at DinkToPdf.WkHtmlToXBindings.wkhtmltopdf_init(Int32 useGraphics)
   at DinkToPdf.PdfTools.Load() in C:\Users\admin\Documents\DinkToPdf\src\DinkToPdf\PdfTools.cs:line 27
   at DinkToPdf.BasicConverter.Convert(IDocument document) in C:\Users\admin\Documents\DinkToPdf\src\DinkToPdf\BasicConverter.cs:line 42
   at DinkToPdf.SynchronizedConverter.<>n__0(IDocument document)
   at DinkToPdf.SynchronizedConverter.<>c__DisplayClass5_0.<Convert>b__0() in C:\Users\admin\Documents\DinkToPdf\src\DinkToPdf\SynchronizedConverter.cs:line 27
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()
   --- End of inner exception stack trace ---
   at DinkToPdf.SynchronizedConverter.Invoke[TResult](Func`1 delegate) in C:\Users\admin\Documents\DinkToPdf\src\DinkToPdf\SynchronizedConverter.cs:line 51
   at DinkToPdf.SynchronizedConverter.Convert(IDocument document) in C:\Users\admin\Documents\DinkToPdf\src\DinkToPdf\SynchronizedConverter.cs:line 27

[rdvojmoc]

Can you please add this class into your project just to test it before i put in the library?

This is custom assembly load context which can load library from absolute path.

internal class CustomAssemblyLoadContext : AssemblyLoadContext
{
	public IntPtr LoadUnmanagedLibrary(string absolutePath)
	{
		return LoadUnmanagedDll(absolutePath);
	}
	protected override IntPtr LoadUnmanagedDll(String unmanagedDllName)
	{
		return LoadUnmanagedDllFromPath(unmanagedDllName);
	}

	protected override Assembly Load(AssemblyName assemblyName)
	{
		throw new NotImplementedException();
	}
}

Create and call CustomAssemblyLoadContext before you create your converter:

CustomAssemblyLoadContext context = new CustomAssemblyLoadContext();
context.LoadUnmanagedLibrary(path);

var converter = new SynchronizedConverter(new PdfTools());

Tested on Windows 10 64bit and Ubuntu LTS 16.04 64bit.

Will this work for your use case?

[joubini]

I was getting similar unable to load dll issues as above. I had no issues after switching to this fork: https://www.nuget.org/packages/RndUsr0.DinkToPdf/. I found it linked from this discussion: https://github.com/rdvojmoc/DinkToPdf/pull/18.

Hopefully this saves someone time from trying the myriad solutions listed in this thread.