There is no finalizer in Domain and Session - as far as I remember, we didn't create them for any of other objects as well, since implicit finalization isn't necessary in our case. All allocated resources are already managed, i.e. if they need such finalizers, they must already have them.

So this might happen because of GC only if you have your own finalizers somewhere.

Other probable causes:

• Wrong order of scope disposal. When outer scope is disposed before inner, our framework disposes inner scope in this case as well. But if inner scope is attempted to be disposed later, this exception is thrown. Probably, we must fix this, since any number of subsequent calls to Dispose must be allowed by IDisposable contract (only first one must lead to actual effects).
• Passing a reference to scope to a different thread, and its subsequent disposal there. Everything is obvious here.