CSharpProvider runtime compilation failing to find a DLL

Question

I am compiling a DLL at runtime using CSharpCodeProvider. My code runs fine on some machines but on otherse it fails with the following error:

error CS0006: Metadata file 'EntityFramework.dll' could not be found

Here is a code snippet:

var csFile = ... // the file is in C:\Program Data\MyFolder\InnerFolder
using (var provider = new CSharpCodeProvider())
{
    var parameters = new CompilerParameters
    {
        GenerateInMemory = false, // we want the dll saved to disk
        GenerateExecutable = false,
        CompilerOptions = "/target:library",

        // the assembly is compiled to the same directory as the .cs file
        OutputAssembly = GetNewCacheAssemblyPath(),
    };

    parameters.ReferencedAssemblies.AddRange(new[]
        {
            "System.dll", 
            "System.Data.dll", 
            "System.Data.Entity.dll", 
            "EntityFramework.dll",
        });

    var compilerResult = provider.CompileAssemblyFromFile(parameters, csFile);
}

Any thoughts as to why this might be happening?

do all the machines have Entity framework installed? If not you may need to installed .Net framework 4 on them or deploy it manually — Amitd, Nov 05 '12 at 15:54
@Amitd: what is the easiest way to determine if this is the case? To my knowlege, all of these machines have .NET 4 installed. These are developer machines where our application (which uses EF is being developed...) — ChaseMedallion, Nov 05 '12 at 16:11
for EF more info on this page.. http://stackoverflow.com/questions/6498388/could-not-locate-assembly-entityframework .. may be there is version difference.. no clue.. also try copying the dlls in the output folder like Hans said — Amitd, Nov 05 '12 at 17:04

score 3 · Accepted Answer · answered Nov 05 '12 at 15:55

EntityFramework is not part of the .NET framework. So a simple explanation is that the machine this fails on doesn't have it installed. You are supposed to deploy it yourself. When you use the Nuget package then you'll have a copy of the DLL in your bin\Release directory. Don't forget to include it with your shipping binaries.

Next failure mode is that you did deploy it but the working directory of the program is not where you hope it is. Provide the full path name of the assembly to avoid this. You can use, say, Assembly.GetEntryAssembly().Location to find the path of the EXE.

The working directory turned out to be a problem. I used reflection to find the path of the EF DLL used by the current application, and then specified the path using a "/lib" compiler option. — ChaseMedallion, Nov 18 '12 at 19:46

score 1 · Answer 2 · answered Nov 05 '12 at 15:57

You mention the code works on some but not on others, it clearly loads all the standard System files properly since they are sequenced before EntityFramework.dll, and it's clear your code itself is generally okay because these standard libraries are not crashing.

It seems rather abundantly clear that the machines it is failing on do not have the Entity framework installed - which makes sense, since it's not part of the .NET native framework. It's an add-on.

CSharpProvider runtime compilation failing to find a DLL

2 Answers2