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

In short

To get this to work also with NCrunch I had to add the Interop.dll versions provided with the NuGet package as additional files in NCrunch configuration.

My case

I had a C# solution with one project directly depending on SQLite (a helper library) and a unit test project that used this helper library. I had installed System.Data.SQLite.Core version 1.0.97.0 as a NuGet package.

In my case the workaround provided by Marin got it working in Visual Studio and in CI as well. However this would still provide errors in NCrunch.

In NCrunch configuration I added the following path in "Additional files to include" under the unit test projects settings:

..\packages\System.Data.SQLite.Core.1.0.97.0\build\net45\**.dll

Answer 2

So, after adding the NuGet the deployment doesn't copy down the Interops. You can add this to your csproj file and it should fix that behavior:

 <PropertyGroup> 
    <ContentSQLiteInteropFiles>true</ContentSQLiteInteropFiles>
    <CopySQLiteInteropFiles>false</CopySQLiteInteropFiles>
    <CleanSQLiteInteropFiles>false</CleanSQLiteInteropFiles>
    <CollectSQLiteInteropFiles>false</CollectSQLiteInteropFiles>
 </PropertyGroup>

If you look in the source for NuGet for SQLite you can see what these are doing specifically. This allowed me to get a deploy working with ASP.Net Core.

Answer 3

even if it is an old post, I'd like to share the solution that I found here: http://system.data.sqlite.org/index.html/info/54e52d4c6f

If you don't want to read all the issue, the solution is to copy the file "msvcr100.dll" (that can be found in Windows\System32 directory) in the same path as SQLite.Interop.dll.

I would advice to read the issue to understand why, and to include the file in your setup but to install it only if the error occurs, I made it an optional component selectable in the setup options.

HTH, Formentz

Answer 4

If you download correct binary for SQLite then copy SQLite.Interop.dll into your Release or Debug folder according to your project build option.

Answer 5

When you get in this state, try performing a Rebuild-All. If this fixes the problem, you may have the same issue I had.

Some background (my understanding):

• SQLite has 1 managed assembly (System.Data.SQLite.dll) and several platform specific assemblies (SQLite.Interop.dll). When installing SQLite with Nuget, Nuget will add the platform specific assemblies to your project (within several folders: \x86, \x64), and configures these dlls to "Copy Always".

• Upon load, the managed assembly will search for platform specific assemblies inside the \x86 and \x64 folders. You can see more on that here. The exception is this managed assembly attempting to find the relevant (SQLite.Interop.dll) inside these folders (and failing).

My Scenario:

I have 2 projects in my solution; a WPF app, and a class library. The WPF app references the class library, and the class library references SQLite (installed via Nuget).

The issue for me was when I modify only the WPF app, VS attempts to do a partial rebuild (realizing that the dependent dll hasn't changed). Somewhere in this process, VS cleans the content of the \x86 and \x64 folders (blowing away SQLite.Interop.dll). When I do a full Rebuild-All, VS copies the folders and their contents correctly.

My Solution:

To fix this, I ended up adding a Post-Build process using xcopy to force copying the \x86 and \x64 folders from the class library to my WPF project \bin directory.

Alternatively, you could do fancier things with the build configuration / output directories.

Answer 6

I know I'm late to the party but I had this issue right after I pulled down latest x86/x64 today (version 1.0.88.0). My local IIS in VS2012 runs 32bit by default and there's no easy way to switch to x64. My production server runs 64bit.

Anyway I installed the NuGet package to a DLL project and I got this error. What I had to do to get it working I had to install it to the main site project, too. Even if it doesn't touch SQLite classes at all.

My guess is that SQLite uses the entry assembly to detect which version of Interop to load.