Loading plug-in DLL files, "The invoked member is not supported in a dynamic assembly."

Question

We have custom DLL's that are not included in our initial setup file. They are loaded at runtime. This process worked fine while using .NET 2.0, but we are getting the "The invoked member is not supported in a dynamic assembly" error message now that we are using .NET 4.0.

try
{
    assem = Assembly.LoadFrom(fi.FullName); //fi is FileSystemInfo
}
catch (FileLoadException) {}
catch (BadImageFormatException) {}
catch (System.Security.SecurityException) {}
catch (ArgumentException) {}
catch (PathTooLongException) {}

Solution 1

This error is occurring because Assembly.Load cannot be called upon dynamic assemblies. You must filter out the dynamic assemblies before using them.

var assemblies = AppDomain.CurrentDomain.GetAssemblies().Where(p => !p.IsDynamic);

Solution 2

For me this issue was not embedding the license for a Aspose dll: http://www.aspose.com/community/forums/thread/423874/initializing-the-license-file.aspx

Their code injects dynamic assemblies when a license isn't detected, causing their DLLs to fail, as well as a bunch of other code that isn't compatible with dynamic assemblies.

Not sure if this is a common licensing/activation method for ensuring registered use with 3rd party dlls, so I'll post it here for google if it is.

Solution 3

This in the app.config file allows for "plug-in" dll's from remote sources.

<configuration>
   <runtime>
      <loadFromRemoteSources enabled="true"/>
   </runtime>
</configuration>

http://msdn.microsoft.com/en-us/library/dd409252.aspx