This exception signals that an attempt to invoke AppDomain.Unload( ) failed. This indicates that you either tried to unload the default application domain ( AppDomain.CurrentDomain ), the domain has a thread that cannot be stopped , or the domain has already been unloaded. public class CannotUnloadAppDomainException : SystemException { // Public Constructors public CannotUnloadAppDomainException ( ); public CannotUnloadAppDomainException (string message ); public CannotUnloadAppDomainException (string message , Exception innerException ); // Protected Constructors protected CannotUnloadAppDomainException (System.Runtime.Serialization.SerializationInfo info , System.Runtime.Serialization.StreamingContext context ); } HierarchyObject Exception(System.Runtime.Serialization.ISerializable) SystemException CannotUnloadAppDomainException |