Runtime exception: XXX type was not found

Question

MS VS C# 2012

I develope an application that uses MEF to interconnect several binary assemblies loaded from a database. One of its separate plug-in assemblies has dependency on a third party DLL that cannot be included in the main application. When I include that third party dll in the main application's references (plug-in has the reference too), compile and run it then the application runs smoothly. But when I remove that DLL from the main application's references (I do not need it there actually, I need to reference it in the plug-in's project only) and use AppDomain.CurrentDomain.AssemblyResolve event to load the third party DLL assembly from database then it runs OK, but later, at runtime, when the plug-in tries to use a XXX type (located in that third party assembly) the application raises an exception, complaining it cannot find the XXX type in the main assembly. I'm stuck.

Does anyone know what could cause that? Any sane explanation would be very appreciated.

The question moved there: http://stackoverflow.com/questions/17404608/net-mef-runtime-error-cs0234-the-type-or-namespace-name-stioraclesource-do — Arlen Keshabyan, Jul 01 '13 at 12:34

score 0 · Answer 1 · answered Jun 26 '13 at 14:40

0

Though I would love to see an even better approach, my team on a project where MEF was used decided to have the other projects that referenced third party assemblies each perform a post build event like so:

xcopy /Y /I /D "$(TargetDir)*.*" "$(SolutionDir)YourMainProjectNameHere\Bin\$(ConfigurationName)\"

For this to work, of course, said third party references in the other projects need to be set to "Copy Local" as well.

answered Jun 26 '13 at 14:40

UtopiaLtd

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Your mileage may also vary using the `/S` flag up front instead of the `*.*` as part of the source path. – UtopiaLtd Jun 26 '13 at 14:52

score 0 · Answer 2 · answered Jun 26 '13 at 15:03

The assembly resovler search for the dll in it's probing domains. which is by default GAC and Private Bin folder. So if you don't want to keep third party dlls in your main application's bin folder then Either you can install those third party dlls into GAC. Or if you have a specific locations where those dlls could be found then add that path to the probing domin.

Just put this line in your configuration file.

<!-- Adding custom folder of the Private bin to default probing domains -->
<runtime>
  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <probing privatePath="c:\plugins;"/>
  </assemblyBinding>
</runtime>

Alternative you can use Directory catalog and specify a location where the third party dlls are placed.

var catalog = new AggregateCatalog(
  new AssemblyCatalog(System.Reflection.Assembly.GetExecutingAssembly()), 
  new DirectoryCatalog("Extensions"));

Runtime exception: XXX type was not found

2 Answers2