System.Data.SQLite from NuGet, interop dll not copied to output directory

Copy this to your project file:

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

Source: SQLite.Interop.dll files does not copy to project output path when required by referenced project

In my case, the problem was the fact that I was using SQLite inside a class library project that was then used by another WPF (gui type) project.

Solved the SQL.Interop.dll not getting copied to output directory, by using the following Post-Build command, inside Project Properties -> Build Events:

xcopy "$(SolutionDir)packages\System.Data.SQLite.Core.1.0.101.0\build\net451\x86\SQLite.Interop.dll" "$(OutputDir)" /y /f

/y overwrites
/f displays actual filenames being copied

I thought this was happening to, as I was copying the files from my output folder to another location when I deployed them. I missed the fact that the interop files WERE being copied, but they are copied to x64 and x86 folders within your output folder.

If you run msbuild in debug on the project, you can look for references to the CopySQLiteInteropFiles target to ensure that it is running.