Unable to cast transparent proxy to type from AppDomain

c# .net remoting appdomain
Mikayla Hutchinson picture Mikayla Hutchinson · Sep 7, 2010 · Viewed 14k times · Source

I'm trying to create an object in an appdomain:

var type = typeof (CompiledTemplate);
var obj = (CompiledTemplate) domain.CreateInstanceAndUnwrap (
    type.Assembly.FullName, type.FullName);

However, I always get the following error:

Unable to cast transparent proxy to type 'Mono.TextTemplating.CompiledTemplate'.

I'm running on .NET 4.0, not Mono, despite what the namespace might suggest :)

As far as I know, this error happens when .NET thinks that the Type & Assembly do not exactly match in the two domains. However, when debugging, the FullName and Location are identical. Only the Assembly.Codebase property differs - in the child AppDomain its extension is uppercased to "DLL" for some reason.

I've tried adding an AssemblyResolve handler to the AppDomain, which uses Assembly.LoadFrom to load the filename explicitly, but the CodeBase's extension still gets uppercased. Since the original assembly was also loaded with Assembly.LoadFrom (via Mono.Addins), the difference between the CodeBase values seems very strange.

Any suggestions for fixing or working around this problem?

Answer

Sasha Goldshtein picture Sasha Goldshtein · Jan 24, 2011

Could you be running into an issue with assembly load contexts? (e.g. see here) You have a type that's clearly in the load context (because you're using typeof(CompiledTemplate)), but you're saying that the type in the secondary AD is loaded into the load-from context...

Did you check with fuslogvw to determine exactly what assemblies are being loaded? The fuslog trace will also tell you if the assemblies are being loaded into different contexts.

Related questions

AppDomain and MarshalByRefObject life time : how to avoid RemotingException?

When a MarshalByRef object is passed from an AppDomain (1) to another (2), if you wait 6 mins before calling a method on it in the second AppDomain (2) you will get a RemotingException : System.Runtime.Remoting.RemotingException: Object [...] has been disconnected or does …

Read More
How best to communicate between AppDomains?

I have an application that needs to send a moderately high volume of messages between a number of AppDomains. I know that I could implement this using remoting, but I have also noticed that there are cross-domain delegates. Has anyone …

Read More
C# Remoting - How to turn off CustomErrors

I getting the following error when I try to connect to my server app using remoting: A problem seems to have occured whilst connecting to the remote server: Server encountered an internal error. For more information, turn off customErrors in …

Read More