# V3103. A private Ctor(SerializationInfo, StreamingContext) constructor in unsealed type will not be accessible when deserializing derived types.

The analyzer detected a serialization constructor with a strange access modifier.

The following cases are treated as suspicious:

- the constructor is declared with the 'public' access modifier;
- the constructor is declared with the 'private' access modifier, but the type is unsealed.

A serialization constructor is called when an object is deserialized, and must not be called outside the type (except when called by a derived class), so it should not be declared as 'public' or 'internal'.

If a constructor is declared with the 'private' access modifier but the class is not sealed, derived classes will not be able to call this constructor; therefore, deserialization of the members of the base class will be impossible.

Consider the following example:

    [Serializable]
    class C1 : ISerializable
    {
      ....
      private C1(SerializationInfo info, StreamingContext context)
      {
        ....
      }
      ....
    }

The 'C1' class is unsealed, but the serialization constructor is declared as 'private'. As a result, derived classes will not be able to call this constructor and, therefore, the object will not be deserialized correctly. To fix this error, the access modifier should be changed to 'protected':

    [Serializable]
    class C1 : ISerializable
    {
      ....
      protected C1(SerializationInfo info, StreamingContext context)
      {
        ....
      }
      ....
    }

Note. This diagnostic has an additional parameter, which can be configured in the configuration file (*.pvsconfig). It has the following syntax:

    //+V3103:CONF:{ IncludeBaseTypes: true }

With this parameter on, the analyzer examines not only how the 'ISerializable' interface is implemented by the class itself, but also how it is implemented by any of the base classes. This option is off by default.

To learn more about configuration files, see this page.