SerializationException: The type System.IO.FileStream in Assembly mscorlib … is not marked as serializable.

This is a strange problem (or maybe I don't understand it).

My orchestration contains a receiveport that receives a filename, some expression boxes that perform some action on the content of the file and at the end a send shape with custom pipeline. The message being send is the path+filename only, inside the pipeline the stream is replaced with the actual content of the file. So, in the end the content of the file is being transmitted thru the send port. The expression and send shapes are on a Scope shape with transaction type set to None.

Snippet from pipeline:
FileStream fileContent = new FileStream(tempFile, FileMode.Open, FileAccess.Read);
…
newMsgPart.Data = fileContent; // Filename is overwritten with content of the file
newMsg.AddPart("body", newMsgPart, true);
return newMsg

The orchestration works as long as I don't add a Exception handler to the scope.
If I add 1 or more exception handlers, It throws the SerializationException and no files are sent.
If I don't add the exception handler NO error is thrown, nor any log of an error and the file is sent successfully.

I hear you thinking why not receive the content of the file and send it like that.
The file is, to say the least large, like 250 MB, when I handle the content in the orchestration I get other problems like out of memory exceptions.

 Any suggestions? Or ideas.