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"Unable to find an entry point named 'sqlite3_open_interop' in DLL 'SQLite.Interop.dll'."

I am using a C# application to try to connect to a SQLite database. The application uses the library System.Data.Sqlite, version 108. In Visual Studio 2017, my Solution Configuration is Debug, and my Solution Platform is Any CPU. Whenever I build and run the application, I get the following runtime exception:
The exception is unhandled, and the application terminates.
There is, of course, a SQLite.Interop.dll file in my bin\Debug directory. (If there wasn't, the exception would be different.) Specifically, there are two, each in their own subdirectories named x64 and x86. My assumption is that the file in the x86 directory is being used, since the Solution Platform is set to Any CPU. The version of the SQLite.Interop.dll assembly matches that of System.Data.SQLite.dll, being 1.0.108.0.
When I use the following command to interrogate the assemblies:
dumpbin /exports SQLite.Interop.dll
I do find the following line in the output for the x64 version of the assembly:
175 AE 00040750 sqlite3_open_interop
but in the output for the x86 version I do not. Instead, I find this line:
175 26 00037F10 _sqlite3_open_interop#20
which is close, but not a match. So there is indeed no such method as sqlite3_open_interop exposed by the assembly.
I have tried the obvious solution of changing the Solution Platform to x64, but that change leads to another exception (BadImageFormatException) which I don't much want to contend with.
I have tried dropping the reference to System.Data.SQLite and using Nuget to add the most recent version, 1.0.111.0, then cleaning and rebuilding the solution, but all to no effect. The same issue recurs.
Could anyone suggest a solution to this issue? SQLite is widely used, I believe, so I have to think there's a way to work through it.
*Edit1: I tried this project on my home computer, and observed the same difference between the two SQLite.Interop.dll files. The x64 version had a sqlite3_open_interop, while the x86 version had a _sqlite3_open_interop#20. However, the problem did not occur there. So apparently this mangled name "issue" is a red herring. I am still very interested in solving this problem, and would appreciate the assistance of someone who works on System.Data.Sqlite!

Delete your x64 and x86 directory then do a build. It will put the correct version in the folder when the installer does the NuGet check. For some reason, when you upgrade to a newer version, the x64 and x86 folders do not update the interop file in those folders if one already exists.

It turned out the issue was that the assembly was being blocked or disrupted somehow by McAfee Host Intrusion Prevention. The Activity log had the following message:
Attack type: DISA McAfee - Prevent unexpected DLL files from Running
in User AppData and ProgramData folders (Sig Id = 7020)
Which is odd because I don't think my program was executing in either such folder; in fact, there are no such folders, as I am looking at the matter. I was able to fix the issue by moving the program to My Documents.
It's also notable that the exception made no hint of interference by a security scanner.
Sigh. I don't know how generally useful this answer is, but I will leave it here. It might help someone. The admins can remove it if they deem appropriate.

Though its an old thread but nevertheless someone else may face similar issue again. In my case, this error occurs when I try to make connection string with password, since in the latest version of sqlite, ecnryption has been a paid feature that's why it doesn't work in free version. So, to circumvant this issue I restored old version of sqlite (picked from my old project) and it worked ok.
Add following reference in your project:
System.Data.SQLite.dll
Copy following files in binary folder:
System.Data.SQLite.dll.config (Optional)
System.Data.SQLite.xml (Optional)
x64\SQLite.Interop.dll
x86\SQLite.Interop.dll
Where 'x64' and 'x86' are folders
Packages available on nuget have same issue so you need old dll

mono compliling GTK# on windows

I am trying to set up GTK# to work with mono on windows. the install was successful, and I can get windows forms programs to compile with mono. I have GTK# in my PATH. this is what i get when trying to compile it. i don't see the output it's referencing. i really don't know what to do from this point. i have repaired the install, i have reinstalled it, i have rebooted the computer, but it still didn't work.
thx in advance

If you read the Mono's documentation for Gtk#, it says:
To some of you that have used the csc compiler on windows may notice
the “-pkg:” as a little odd. This doesn’t exist in csc because Mono
comes from the world of Linux. What that does is lookup for a package
config file under that name. In the package config folder exists a
file name “gtk-sharp-2.0.pc” which contains (amongst other
information) on the location of the libraries for that package. That
way we don’t have to type out “-r:gtk-sharp-2.0.dll
-r:atk-sharp-2.0.dll -r:pango-sharp-2.0.dll ….” all by hand.
One would assume that, provided the docs, everything needed to compile is present, including pkg-config, the executable that actually reads the gtk-sharp-x.y.pc file and configures the compilation. However, either it does not exist, or the PATH has not been correctly configured.
First of all get sure that you have installed Mono and Gtk#. I know it seems it is redundant, but both installers are needed.
Then, decompose the compilation command so pkg-info is not needed.
$ mcs -r:/usr/lib/mono/gtk-sharp-2.0/gtk-sharp.dll -r:/usr/lib/mono/gtk-sharp-2.0/atk-sharp.dll -r:/usr/lib/mono/gtk-sharp-2.0/glib-sharp.dll gtksharpdemo.cs
I'm in a Linux machine, so the complete paths to the assemblies won't be those ones. I guess it will be something like:
$ mcs -r:"C:\Program Files (x86)\Mono\lib\gtk-sharp-2.0\gtk-sharp.dll" -r:"C:\Program Files (x86)\Mono\lib\gtk-sharp-2.0\glib-sharp.dll" -r:"C:\Program Files (x86)\Mono\lib\gtk-sharp-2.0\atk-sharp.dll" gtksharpdemo.cs
Finally, this is all much easier if you work with MonoDevelop. You can start your project from the Gtk# 2.0 template, and everything will be set up for you. If you prefer to start from the empty template for some obscure reason, then go to the "references" section of the project, and add "System", "gtk-sharp", "glib-sharp", and "atk-sharp".
This is also all possible from Visual Studio, but I don't have any experience using it.

Unpredictable System.DllNotFoundException

I downloaded a package from SourceForge, PlanEph, which has 64 and 32 bit DLLs for C#. I got the 32 bit included C# demo to work by putting the DLL in my bin/Debug directory (I'm using Visual Studio 2015 Community) and adding the DLL as a reference.
Then I tried to make my own version of the demo in a separate solution, and got the System.DllNotFoundException. Various experimentation lead me to believe I can't have two identical namespace names anywhere in my Visual Studio installation, so I erased everything and started over.
I made a directory C\GJAbin, put the DLL in it, and added it to the system Path variable. I also put a helloWorld type program in that dir and executed it from the command line to verify the directory really was in the path. Then I recreated the demo solution, added the DLL as a resource, and built the solution "successfully". Then I ran it and got the System.DllNotFoundException.
So I can't understand why the DLL is being found when compiling but not at run time.

Go to project settings, go to "publish" tab and on the top most button (labeled something like "application files"). Chose "Show all files" checkbox if you don't see your DLL. Set the DLL's publish status to "Include" (NOT "Include (Auto)"!!) and publish it again.
Now the DLL should be inside the publish folder.

So I can't understand why the DLL is being found when compiling but not at run time.
Locating the assembly at compile time is done differently (by MSBuild) than at runtime (by the CLR).
At compile time, MSBuild has specific search paths that it knows about, or in most cases like this, there will be something in your project file telling MSBuild where to look for the file. Usually the <Reference> has a <HintPath>.
At runtime, the CLR will attempt to find the assembly from its own set of well-known paths. It will look in your app's config file (if applicable), then in the Global Assembly Cache (GAC), then in your app's root directory. Much more detail on this is available here.
You can tell MSBuild to copy the reference to your build output directory (usually the same as your app root directory when running). In VS, you can do this by selecting the reference and looking at the Properties tool window (or press F4 by default). Set the CopyLocal state to True. In the project file, this will add a <Private>True</Private> on the <Reference>.
You can also add the assembly to the GAC using the gacutil tool, but this does make it harder if you want to share your app with others. Usually it's preferable to keep a copy in your app root directory.
If it's still not working, you can also see the log for how the runtime is trying to find this assembly. The fuslogvw.exe tool in the Windows SDK (you can run it from the VS command prompt and it will be on the %PATH%) allows you to enable logging for assembly loads. You do need to be able to run this as an administrator to configure the setting.
As you can see in the screenshot, you can either log the results in the exception (so that you can see it while debugging), or you can log it to a file on disk (so you can see it whenenver).

The problem turned out to be an unfortunate interaction among the way the author chose names and the way Visual Studio displays information and error messages. The author created a c# dll Astronomy.PlanEph32.dll containing a namespace PlanEph32, which which was really just a wrapper for the c dll PlanEph32.dll. So all the error messages about not being able to load PlanEph32.dll were referring to not finding the c dll; the c# dll was being found just fine.

Possible reasons for assembly / file not found?

I'm working in a team that has created a solution. In the solution we have 4 projects (data access, business logic and unit tests and common things).
BL references DA and CT
CT references DA
UT references BL and CT
Now whenever I rebuild it brings no errors. On my collegues PC it works without a hitch but on my PC whenever I try to run an unit test I get the following error (translated manually into english so any typos are my fault while writing this question):
{"The file or assembly \"MyWorkspaceName.MySolutionname.CT,
version=0.2.0.0, Culture=neutral, PublicKeyToken=null\" or a reference
of it was not found. The system cannot find the given
file.":"MyWorkspaceName.MySolutionname.CT, version=0.2.0.0,
Culture=neutral, PublicKeyToken=null"}
As that version and name exists (it is the common things part I manually checked if it exists) and I also checked the refernces inside of the CT if they are correct.....I'm not sure what could be a possible reason for it not working for me (but working on my collegues PC).
Thus my question would be: What could be possible reasons for that error message?
Update:
CT is now found but when I try to access the DA from BL it says the same error as before just with DA instead of the CT (ran from the UT part).
When I run the SAME methods from a console application project created within the same solution, they work without throwing any error.

There are three possibilities,
Different CPU architectures, if your colleague's PC is x64 and yours is x86 then DLL reference setup in projects might differ and that could give this error.
Different folder structures.
Different third party references, see the details below.
Are you sure you have installed every third party tools/libraries that are there on your colleague's PC?
Most probably third party references should be added as NuGet packages but if your project references third party assembly which in turn references another assembly installed via some installer and which is absent on your machine, you may get similar error. I had similar problems and some native libraries do not show up in error as dependencies unless you turn on assembly log and investigate.

Did you try to delete /obj and /bin folder before rebuilding? Sometimes there are old assembly reference caches which mess the build process.
Here is a PowerShell script for recursive erase of /bin and /obj folders. Just run it in the main solution folder.
Get-ChildItem .\ -include bin,obj -Recurse | foreach ($_) { remove-item $_.fullname -Force -Recurse }
Another possible problem that I have encountered is when there is a difference between assemblies installed in the GAC and locally downloaded NuGet packages. - Your VS gets the DLL from GAC but on your team mates computers the DLL comes from NuGet and it is different version.
To get the assembly binding information in VS : Tools -> Options -> Projects And Solutions -> Build And Run -> MS Build project build output verbosity -> Set to Diagnostic and when you build Copy-Paste the diagnostic info into notepad++ and search for 'error' and 'conflict' then resolve.

Usually if I can't solve such issues in a meaningful amount of time I go for help to Process Monitor
In your case I would add a not too restrictive filter such as: Path contains .dll and look for failure results during application launch. This might reveal what actual dll files could not be found and places were they were looked for.

Visual Studio works on a trust system, meaning you have to explicitly trust network drives. have you tried to copy the project to your local hard drive to see if it works?
Here is the article from microsoft on how to change the trusts using the CasPool.exe tool.
Caspol.exe (Code Access Security Policy Tool)
Just a few notes about this so you don't miss anything. There is different trusts for both 32-bit and 64-bit applications, so make sure you apply the trust to both to avoid any issues.
Before you go through the trouble of this tool, I would highly recommend that you copy to your local hard drive first and see if that is indeed the problem.

ILMerge Best Practices

Do you use ILMerge? Do you use ILMerge to merge multiple assemblies to ease deployment of dll's? Have you found problems with deployment/versioning in production after ILMerging assemblies together?
I'm looking for some advice in regards to using ILMerge to reduce deployment friction, if that is even possible.

I use ILMerge for almost all of my different applications. I have it integrated right into the release build process so what I end up with is one exe per application with no extra dll's.
You can't ILMerge any C++ assemblies that have native code.
You also can't ILMerge any assemblies that contain XAML for WPF (at least I haven't had any success with that). It complains at runtime that the resources cannot be located.
I did write a wrapper executable for ILMerge where I pass in the startup exe name for the project I want to merge, and an output exe name, and then it reflects the dependent assemblies and calls ILMerge with the appropriate command line parameters. It is much easier now when I add new assemblies to the project, I don't have to remember to update the build script.

Introduction
This post shows how to replace all .exe + .dll files with a single combined .exe. It also keeps the debugging .pdb file intact.
For Console Apps
Here is the basic Post Build String for Visual Studio 2010 SP1, using .NET 4.0. I am building a console .exe with all of the sub-.dll files included in it.
"$(SolutionDir)ILMerge\ILMerge.exe" /out:"$(TargetDir)$(TargetName).all.exe" "$(TargetDir)$(TargetName).exe" "$(TargetDir)*.dll" /target:exe /targetplatform:v4,C:\Windows\Microsoft.NET\Framework64\v4.0.30319 /wildcards
Basic hints
The output is a file "AssemblyName.all.exe" which combines all sub-dlls into one .exe.
Notice the ILMerge\ directory. You need to either copy the ILMerge utility into your solution directory (so you can distribute the source without having to worry about documenting the install of ILMerge), or change the this path to point to where ILMerge.exe resides.
Advanced hints
If you have problems with it not working, turn on Output, and select Show output from: Build. Check the exact command that Visual Studio actually generated, and check for errors.
Sample Build Script
This script replaces all .exe + .dll files with a single combined .exe. It also keeps the debugging .pdb file intact.
To use, paste this into your Post Build step, under the Build Events tab in a C# project, and make sure you adjust the path in the first line to point to ILMerge.exe:
rem Create a single .exe that combines the root .exe and all subassemblies.
"$(SolutionDir)ILMerge\ILMerge.exe" /out:"$(TargetDir)$(TargetName).all.exe" "$(TargetDir)$(TargetName).exe" "$(TargetDir)*.dll" /target:exe /targetplatform:v4,C:\Windows\Microsoft.NET\Framework64\v4.0.30319 /wildcards
rem Remove all subassemblies.
del *.dll
rem Remove all .pdb files (except the new, combined pdb we just created).
ren "$(TargetDir)$(TargetName).all.pdb" "$(TargetName).all.pdb.temp"
del *.pdb
ren "$(TargetDir)$(TargetName).all.pdb.temp" "$(TargetName).all.pdb"
rem Delete the original, non-combined .exe.
del "$(TargetDir)$(TargetName).exe"
rem Rename the combined .exe and .pdb to the original project name we started with.
ren "$(TargetDir)$(TargetName).all.pdb" "$(TargetName).pdb"
ren "$(TargetDir)$(TargetName).all.exe" "$(TargetName).exe"
exit 0

We use ILMerge on the Microsoft application blocks - instead of 12 seperate DLL files, we have a single file that we can upload to our client areas, plus the file system structure is alot neater.
After merging the files, I had to edit the visual studio project list, remove the 12 seperate assmeblies and add the single file as a reference, otherwise it would complain that it couldnt find the specific assembly. Im not too sure how this would work on post deployment though, could be worth giving it a try.

I know this is an old question, but we not only use ILMerge to reduce the number of dependencies but also to internalise the "internal" dependencies (eg automapper, restsharp, etc) that are used by the utility. This means they are completely abstracted away, and the project using the merged utility doesn't need to know about them. This again reduces the required references in the project, and allows it to use / update its own version of the same external library if required.

We use ILMerge on quite a few projects. The Web Service Software Factory, for example produces something like 8 assemblies as its output. We merge all of those DLLs into a single DLL so that the service host will only have to reference one DLL.
It makes life somewhat easier, but it's not a big deal either.

We had the same problem with combining WPF dependencies .... ILMerge doesn't appear to deal with these. Costura.Fody worked perfectly for us however and took about 5 minutes to get going... a very good experience.
Just install with Nuget (selecting the correct default project in the Package Manager Console). It introduces itself into the target project and the default settings worked immediately for us.
It merges the all DLLs marked "Copy Local" = true and produces a merged .EXE (alongside the standard output), which is nicely compressed in size (much less than the total output size).
The license is MIT as so you can modify/distribute as required.
https://github.com/Fody/Costura/

Note that for windows GUI programs (eg WinForms) you'll want to use the /target:winexe switch. The /target:exe switch creates a merged console application.

I'm just starting out using ILMerge as part of my CI build to combine a lot of finely grained WCF contracts into a single library. It works very well, however the new merged lib can't easily co-exist with its component libraries, or other libs that depend on those component libraries.
If, in a new project, you reference both your ILMerged lib and also a legacy library that depends on one of the inputs you gave to ILMerge, you'll find that you can't pass any type from the ILMerged lib to any method in the legacy library without doing some sort of type mapping (e.g. automapper or manual mapping). This is because once everything's compiled, the types are effectively qualified with an assembly name.
The names will also collide but you can fix that using extern alias.
My advice would be to avoid including in your merged assembly any publicly available lib that your merged assembly exposes (e.g. via a return type, method/constructor parameter, field, property, generic...) unless you know for sure that the user of your merged assembly does not and will never depend on the free-standing version of the same library.

We ran into problems when merging DLLs that have resources in the same namespace. In the merging process one of the resource namespaces was renamed and thus the resources couldn't be located. Maybe we're just doing something wrong there, still investigating the issue.

We just started using ILMerge in our solutions that are redistributed and used in our other projects and so far so good. Everything seems to work okay. We even obfuscated the packaged assembly directly.
We are considering doing the same with the MS Enterprise Library assemblies.
The only real issue I see with it is versioning of individual assemblies from the package.

I recently had issue where I had ilmerged assembly in the assembly i had some classes these were being called via reflection in Umbraco opensource CMS.
The information to make the call via reflection was taken from db table that had assembly name and namespace of class that implemented and interface. The issue was that the reflection call would fail when dll was il merged however if dll was separate it all worked fine. I think issue may be similar to the one longeasy is having?

It seems to me like the #1 ILMerge Best Practice is Don't Use ILMerge. Instead, use SmartAssembly. One reason for this is that the #2 ILMerge Best Practice is to always run PEVerify after you do an ILMerge, because ILMerge does not guarantee it will correctly merge assemblies into a valid executable.
Other ILMerge disadvantages:
when merging, it strips XML Comments (if I cared about this, I would use an obfuscation tool)
it doesn't correctly handle creating a corresponding .pdb file
Another tool worth paying attention to is Mono.Cecil and the Mono.Linker [2] tool.
[2]: http:// www.mono-project.com/Linker