Unable to load DLL 'SQLite.Interop.dll'

Question

Periodically I am getting the following exception:

Unable to load DLL 'SQLite.Interop.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)

I am using 1.0.82.0. version, installing it with nuget in VS2010, OS Win7 64.

Once exception starts to appear, it appears constantly - in debug and release and running application within or outside VS.

The only way to stop it is logoff and logon. The exception is not thrown and dll is loaded. It can work for days, but then it can break again.

Has anyone seen something like this and is there a solution for it?

Answer 1

This is how I fixed it in my project.

It was working, and when a colleague submitted his changes, I received the "Unable to load DLL 'SQLite.Interop.dll'" exception.

Diffing the project's .csproj file, this was in the NON-WORKING version:

<ItemGroup>
     <Content Include="x64\SQLite.Interop.dll" />
     <Content Include="x86\SQLite.Interop.dll" />
</ItemGroup>

And this is what the WORKING version had:

<ItemGroup>
     <Content Include="x64\SQLite.Interop.dll">
          <CopyToOutputDirectory>Always</CopyToOutputDirectory>
      </Content>
      <Content Include="x86\SQLite.Interop.dll">
          <CopyToOutputDirectory>Always</CopyToOutputDirectory>
      </Content>
</ItemGroup>

After reverting back, I didn't receive the exception. The DLL files were dumped in the appropriate Debug\x64 (etc) folders.

Answer 2

I don't know why this has not been included yet, but I had to do the research and find this out for myself, so hopefully someone will find this answer and be saved the trouble. This was for a WPF app. It worked fine on my Dev box, but did not work on the computer where I was copying it and got the Unable to load DLL 'SQLite.Interop.dll' error. I ported over all of its associated directories and files, directly from my "Debug" folder to this other computer when I got the same error as the OP when I ran it. My "bin" folder that contained my DLLs had been copied to "Debug\bin" and all were included, along with my application files when I did my copying to the other computer using this path, so it was not missing any files.

Things I saw said in other answers that did not apply:

• I did not use the NuGet package or need to create x86 or x64 folders that it seems that NuGet package creates. My DLLs (System.Data.SQLite and SQLite.Interop.dll, along with System.Data.SQLite.config) are in the "bin" folder in my project and were copied in manually (create "bin" folder in Solution Explorer in VS, paste DLLs into this folder in Windows Explorer, use Add > Existing Item to bring files into VS folder/project). Then I reference them as Referenced Assemblies in my project using that location ("References" > "Add Reference", and browse to one, rinse, repeat for the rest). This ensures my project knows exactly where they are.
• I did not need to reference any SQLite DLL file in my app.config or even touch my MyProject.csproj file.
• I did not even need to specify a particular processor! My project's build is for "Any CPU", even though I have only mixed or 64-bit DLLs and will only be running on Windows 7+, which are 64-bit OSes. (no x86-only/32-bit solely DLLs)
• I was already specifying them as "Content" and "copy if newer" for these DLLs when I experienced the OP's error.

What I found was this, from https://system.data.sqlite.org/index.html/doc/trunk/www/faq.wiki#q20 :

(11) Why do I get a DllNotFoundException (for "sqlite3.dll" or "SQLite.Interop.dll") when trying to run my application?

Either the named dynamic link library (DLL) cannot be located or it cannot be loaded due to missing dependencies. Make sure the named dynamic link library is located in the application directory or a directory along the system PATH and try again. Also, be sure the necessary Visual C++ runtime redistributable has been installed unless you are using a dynamic link library that was built statically linked to it.

Emphasis mine on that bolded part inside the paragraph. The target computer was fresh and had no programs loaded except .NET 4.0. Once I installed C++, it was able to complete the commands to SQLite. This should have been one of the first FAQs and part of the pre-requisities, but it was buried at #11. My development computer already had it loaded because it came with Visual Studio, so that's why it worked, there.

Download:
Visual C++ Redistributable for Visual Studio 2015:
https://www.microsoft.com/en-us/download/details.aspx?id=48145

Update 3 (cumulative update):
https://www.microsoft.com/en-us/download/details.aspx?id=53587

Answer 3

I don't know if it's a good answer, but I was able to solve this problem by running my application under an AppDomain with an identity of "Local System".

Answer 4

For reference for anyone looking at this question:

If you use the nuget package, it installs a build rule that does the copying for you. (see under System.Data.SQLite.Core.1.0.94.0\build - or whatever version of Core you install).

The nuget installer adds the rule to your project file automatically.

This still doesn't fix the test case problem though. The DeploymentItem (https://stackoverflow.com/a/24411049/89584) approach is the only thing that seems to work there.

Answer 5

I got the same problem. However, finally, I can fix it. Currently, I use Visual Studio 2013 Community Edition. I just use Add->Existing Item... and browse to where the SQLite.Data.SQLite files are in (my case is 'C:\Program Files (x86)\System.Data.SQLite\2013\bin'). Please don't forget to change type of what you will include to Assembly Files (*.dll; *.pdb). Choose 'SQLite.Interop.dll' in that folder. From there and then, I can continue without any problems at all. Good luck to you all. ^_^ P.S. I create web form application. I haven't tried in window form application or others yet.

Answer 6

I had this problem because Visual C++ 2010 redistributable no installed in my PC.if you have not already installed Visual c++ 2010 redistributable Download and install this(check x86 or 64 dll).